Terms to watch out for

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a lot, alot

The correct spelling is a lot, not alot:

I put a lot of onions in the sauce.

Aboriginal, Aborigine

Aboriginal is an adjective; Aborigine is a noun (eg Aborigines are Aboriginal people). Note that Aborigine should not be used. An Aboriginal person is defined legally as someone who is a descendant of an Aboriginal inhabitant of Australia, sees themselves as an Aboriginal person, and is recognised as Aboriginal by members of the community in which they live or have lived.

absorption, adsorption

absorption: the taking up of one thing by another through (for example) capillary, chemical or molecular action

The sponge absorbed the water.
Digested food is absorbed by the gut.

adsorption: the holding of something on a surface

The protein adsorbed to the membrane.

accept, except

accept: to receive willingly (verb)

The politician should not accept that gift.

except: to leave out (verb)

The teacher will except the students who are ill. 

accuracy, precision

accuracy: the closeness of a measurement to the expected or ‘true’ value; the correctness of a statement

The spectrometer was more accurate after it was calibrated.
His assertion that Earth is flat was inaccurate.

precision: the closeness of measurements to each other (ie the ‘spread’ of the data); the degree of specificity of a measurement

The similarity of the replicates demonstrates the precision of the method.
3.14159 is more precise than 3.1.

adaptation, adaption

These have the same meaning (an adjustment or alteration, or something produced by an adjustment or alteration). Adaptation is the more accepted alternative, and adaption should be avoided.



affect, effect

affect (verb): to have an influence on, alter, cause a change in

Changing the pH of the solution may affect [alter for better or worse] the result.

affect (noun): observable feeling or emotion, or subjective experience of emotion associated with a thought

Most subjects in the trial showed a happy affect in response to the photos of the puppies.

effect (verb): to bring about, cause, produce, result in

Changing the pH of the solution can effect [bring about] a colour change.

effect (noun): the result of a change

The effect of changing the pH of the solution is ...


AIDS (acquired immunodeficiency syndrome): the disease that can result from infection with HIV (human immunodeficiency virus). It is incorrect to refer to the AIDS virus (the virus is HIV, not AIDS), AIDS-infected people (people are infected with HIV, not AIDS) or AIDS test (it is not possible to test for AIDS).

HIV (human immunodeficiency virus): the virus that causes AIDS. Note that not all people who are HIV-positive have AIDS.

aliquot, sample

aliquot: one of the parts of a total amount of a gas, liquid or solid that has been completely divided into equal parts

1 mL is an aliquot of 10 mL

sample: a part taken as representative of its source for analysis or study

We collected a 100-mL sample of pond water, which was divided into 10-mL aliquots.

allele, gene, gene product, locus

allele: any alternative form of a particular gene. Different alleles often confer different phenotypes

gene: a section of a DNA molecule (or RNA molecule, in some viruses) that contributes to a particular function or phenotype

gene product: the ribonucleic acid (RNA) or protein that is the product of the gene being expressed (transcribed or translated). The RNA or protein often has a name that is the same as, or similar to, the name of the gene, so it is important to distinguish between these entities

locus: the mapped location of a DNA sequence; it is not a synonym for gene. Loci is the plural of locus. See also Chromosomal location

alternate, alternative (as adjectives)

alternate: relating to every second item in a series

The beetle had alternate stripes of red and brown.

alternative: relating to a choice between 2 or more things

We considered 3 alternative designs for the experiment.


amount, concentration, level

amount: quantity of a substance

concentration: quantity of a substance in a unit volume or mass of another substance

level: a measure of some quantitative property of a substance (eg mass, concentration, height). For clarity, level should be avoided if a more precise term, such as concentration, could be used instead

analogue, homologue, homeologue

analogue (noun): in organic chemistry, a compound that is structurally similar to another (structural analogue) or performs the same functions (functional analogue); in biology, an organ or part with a different origin but the same function (eg the wings of a bee and the wings of a bird)

analogous (adjective): in evolutionary biology, referring to organs that have the same function or are similar in appearance but are not equivalent morphologically and did not evolve from the same organs (eg the wings of a bee and the wings of a bird)

analog (adjective): referring to information that is not digital, or a device that records information in a way that is not digital (ie properties are encoded in terms of frequencies and their amplitudes)

homologue (noun), homologous (adjective): in evolutionary biology, refers to things that have the same structure and origin but not necessarily the same function or appearance (eg the wing of a bird and the foreleg of a horse). In genetics, describes a pair of chromosomes (one from the mother and one from the father) that have the same genes at the same loci. In molecular biology, describes sequences (DNA or protein) with a shared ancestry. In chemistry, describes a series of organic compounds of the same chemical type, but differing by a fixed increment in a repeating unit, or chemical elements that occur in the same group of the periodic table and share some electrochemical properties. In medicine, relates to an antiserum in which the antibodies correspond to the antigenic material that was used to produce the antiserum. Also sometimes used in developmental psychology to indicate behaviours that have common origins

homeologue: in molecular biology, homeologous chromosomes are chromosomes from different species that are partly similar as a result of a common ancestor (ie only partly homologous)

anatomy, morphology

anatomy: physical structure and composition of an animal or plant, or the study of this area

morphology: form and structure of an animal or plant, or the study of this area. Anatomy is a subset of morphology

antibiotic, antimicrobial, antiviral

antibiotic: a chemical substance that kills or inhibits the growth of bacteria (a more precise term is antibacterial)

antimicrobial: a chemical substance that kills or inhibits the growth of microorganisms; this is a broader term than antibiotic, since it includes antibacterials (active against bacteria), antifungals (active against fungi; also known as antimycotics) and antiparasitic agents (active against parasites)

antiviral: a chemical substance that inhibits the replication of viruses and is used to treat viral infections. In contrast, viricides inactivate viruses, either within or outside the body

antivenene, antivenin, antivenom

Alternative terms for a biological product used in the treatment of venomous bites or stings.
Antivenom is the preferred term in Australia.

asteroid, meteor, meteorite, meteoroid

asteroid: a minor planet (with a diameter between 1 km and several hundred kilometres), especially in the inner Solar System (between Mars and Jupiter)

meteor: a streak of light that is seen when a meteoroid enters Earth’s atmosphere; often called a ‘shooting star’ or a ‘falling star’

meteorite: a meteoroid that falls to Earth’s surface

meteoroid: a solid body travelling through space that is smaller than an asteroid; mostly the remnants of comets or asteroids. When a meteoroid enters Earth’s atmosphere, heating results in its becoming visible as a meteor

autopsy, necropsy, postmortem

All 3 words refer to examination of the body of an animal after death. Necropsy tends to be used to refer to nonhuman animals, and autopsy to humans, whereas postmortem can refer to either. Postmortem can be used as either a noun or an adjective (eg postmortem findings).

average, mean, median, mode

average: a general term usually used to mean the arithmetic mean, but may be incorrectly used to mean median or mode

mean: the sum of a set of values divided by the number of values (arithmetic mean)

median: the central value in a set of values ordered by value

mode: the most frequent value in a set of values

because, due to

because: as a result of

due to: attributable to, caused by, resulting from

A grammar ‘rule’ is that due to should only be used as an adjective (following the noun), and not as a compound preposition. It should not be used in place of because of:

The colour change was due to a chemical reaction.


Due to a chemical reaction, the solution changed colour.


The solution changed colour due to a chemical reaction.

Use of due to in a sentence is only correct if these words could be replaced by caused by or attributable to. Due to should not be used as a wordy alternative to because.

benzene, benzine

benzene: a single species of hydrocarbon molecule (which, confusingly, was originally called benzine!)

benzine: a mixture of hydrocarbons obtained in the distillation of petrol


billion, trillion (-illion)

The meaning of billion and other large numbers may depend on the country in which they are used or, more probably these days, the age of the writing in which they appear. The original meanings were easy to decipher, following the bi, tri, quad sequence (2, 3, 4, etc) that is found in other words (bilingual, tricycle, quadruped, etc). Thus billion was 2 millions multiplied or 1 000 0002 (1012), trillion meant 1 000 0003 (1018), quadrillion meant 1 000 0004 (1024), and so on. European scientists began to change this by a factor of 10, and Americans followed, so that 1 billion became 1 000 000 000 1000 million, or 109), and the rest of the sequence was similarly changed to 1012 and 1018. Today, 1 billion is taken to mean 1000 million (109), but its meaning may be ambiguous where it is encountered in writing from the past. Some scientists and communicators, especially when their audience is likely to be international, prefer to use the explicit 1 thousand million or 1 million million to make their meaning unambiguous. See also Numbers and units

biodegradable, compostable, recyclable

biodegradable: capable of being decomposed by the action of living organisms, especially bacteria

compostable: made of a material that is suitable for forming compost

recyclable: capable of being treated so that new products can be manufactured from the original material, or made of a material that can be adapted or reconstructed for a second use

bioengineering, biomedical engineering, biotechnology

bioengineering: the combination of biology and engineering to advance medical interventions

biomedical engineering: interchangeable with bioengineering

biotechnology: the use of any living organism to make or change a product

blackwater, greywater, wastewater

blackwater: dark water in water bodies such as rivers and waterholes, resulting from decay of excessive organic matter and consequent sudden depletion of oxygen in the water, OR raw sewage

greywater: domestic wastewater (eg from washing machines or baths); often reused for purposes other than drinking (eg watering gardens), rather than being drained into the sewerage system

wastewater: water that is degraded in quality and originates from various sources, including homes, industries and surface runoff

breed, species

breed (animals): an animal husbandry term for animals of the same species that have been artificially (by humans) selected to have certain characteristics that they pass on to their offspring

species: a taxonomic term for a group of organisms than can naturally reproduce with each other, and produce healthy and reproductively viable offspring

breeding line, germplasm

breeding line: a group of pure-breeding organisms with a unique phenotype or genotype that distinguishes them from other individuals of the same species

germplasm: a collection of genetic resources for an organism. For plants, the germplasm can be a seed, part of the plant (cutting) or seedling. Animal genetic resources include reproductive cells (sperm, eggs), tissue samples, stem cells and embryos. Plant genetic resources may be stored in a seed bank or nursery. Animal or plant genetic resources may be stored in a gene bank or cryobank

bug, germ, microbe, microorganism

bug: specifically, a kind of insect with piercing and sucking mouthparts (family Hemiptera), but ubiquitously used as an inaccurate term for ‘invertebrate’, ‘illness’, ‘microorganism’, ‘computer fault’ and much more. Unless it is being used to describe a hemipteran insect, it should be avoided unless the writing is colloquial and the context makes the meaning clear

germ: another imprecise term used in writing about science, usually to refer to a pathogen (a microorganism that can cause disease). Germ cells are cells that give rise to the gametes of a sexually reproducing organism

microbe and microorganism: synonymous terms that refer to any microscopic organism, either single celled or multicellular, including bacteria, fungi, protozoa and algae. Viruses are sometimes considered to be microorganisms (although it can be argued that viruses are not living organisms). Microbe or microorganism, rather than bug or germ, is the preferred collective term when discussing microscopic agents in the context of health and disease

can, may, might

can: to be able

Dogs can see a smaller range of colours than humans.

may: expressing uncertainty, or to be possible

He may be correct in his assumption.
The mixture may separate into 2 phases.
You may apply during the 3 months before the closing date.

might: expressing strong uncertainty

We might be able to obtain government funding, but it is unlikely this year.

cancer, neoplasm, tumour

cancer: a malignant neoplasm

neoplasm: a blanket term referring to an uncontrolled growth of abnormal cells in either humans or animals. Neoplasms may be benign (do not invade surrounding tissues or spread to other parts of the body) or malignant (invade surrounding tissues and spread to new sites in other parts of the body)

tumour: a neoplasm that forms an abnormal solid mass of tissue (in contrast to neoplasms such as leukaemia, which do not form tumours). Tumours can be benign or malignant

carcase, carcass

These 2 spellings are usually used interchangeably (in Australia and other English-speaking countries). However, in some specialist publications (notably the national, state and territory departments of agriculture), a distinction in meaning is made between the spellings:

  • carcase: the body of an animal that has been slaughtered for meat (eg at an abattoir)
  • carcass: the body of an animal that has died from natural causes, including disease or injury.


carry out, perform

Both these terms are a sign of weak and passive constructions:

The tests were carried out on the samples
The pond sampling was performed at 6.00 am

Avoid these constructions and improve your writing by activating the verbs that are hiding as nouns:

We tested the samples    or    The samples were tested
The pond was sampled at 6.00 am    or    We sampled the pond at 6.00 am

See also Active versus passive voice

case–control study, cohort study

case–control study: an observational study design in which the history of a group of participants with a specific outcome (eg a disease) is compared with the history of a matched group without the outcome – for example, comparison of the previous drinking habits of people with cancer and people without cancer

cohort study: an observational study design in which a cohort of participants with a specific treatment, exposure or condition is followed over a period and compared with a matched group with a different treatment, exposure or condition – for example, comparison of the long-term outcomes of cohorts of children brought up in areas with and without fluoride in the drinking water

cell cycle, cell division

cell cycle: the period from one cell division to the same point in the next

cell division: the formation of 2 cells (daughter cells) from one cell (parent cell)

cell division

cell line

cell strain, cell line

cell strain: cultured tissue cells that will not divide indefinitely. Cell strains only divide a limited number of times before they die (referred to as the Hayflick limit)

cell line: cell cultures of specific human or animal cells that will divide indefinitely, provided they are maintained properly. Cell lines have escaped the Hayflick limit and are immortal

Celsius, centigrade

Celsius: relating to the temperature scale in which water freezes at 0 degrees Celsius (0 °C) and boils at 100 °C at standard atmospheric pressure (760 mmHg); the temperature on the Celsius scale is the temperature in kelvins minus 273, and a degree Celsius is equal to a kelvin. Named after the Swedish astronomer Anders Celsius

centigrade: the historical name for the Celsius temperature scale. Named from the Latin (centum = 100, gradus = steps)


characteristic, parameter, variable

characteristic: a property of an item; subtly different from a parameter (see below) because parameters define function – for example, colour is a characteristic of a car or train, but does not affect function

parameter (general): limits or boundaries of a system (eg the parameters of the project)

parameter (mathematics): a measurable factor (variable or constant) that defines a system. For example, a steam train and an electric train have different parameters for creating motion. In either case, speed is a variable (see below)

variable (general science, research): an attribute of a system. Some variables have only 2 possible values (yes/no; on/off) and are called binary, or dichotomous variables; some variables can have any of a range of values (eg age, height) and are called continuous. One of the most important elements of the scientific method is the isolation of different variables, subjecting one to experimentation by varying it while controlling the others

variable (mathematics): a symbol that represents an unknown quantity in a mathematical expression (compared with a known quantity, or constant)

climate change, climate variability, global warming, global change, greenhouse effect

climate change: the long-term change in Earth’s weather patterns. Although the term is often used to refer to anthropogenic climate change – that is, caused by human activities, such as burning fossil fuels and mass deforestation – Earth system events, such as volcanic eruptions and tectonic plate movements, also contribute to climate change

climate variability: the year-to-year change seen in regional weather; should not be used interchangeably with climate change

global warming: the increasing average global air temperature that is associated with climate change

global change: planetary-scale changes in atmospheric circulation, ocean circulation, climate, the carbon cycle, the nitrogen cycle, the water cycle, sea ice, sea level, food webs, biological diversity, pollution, health and so on

greenhouse effect: the process by which radiation from a planet’s atmosphere warms the surface of the planet to a temperature above what it would be in the absence of an atmosphere. Anthropogenic climate change is sometimes referred to as the enhanced greenhouse effect

climate, weather

climate: the weather conditions prevailing in an area in general, or over a particular period

weather: the temperature and conditions of cloudiness, dryness, sunshine, wind, rain and so on, at a particular place and time

clinical study, clinical trial

clinical study: observational study design for making epidemiological observations of the effects of different clinical treatments or exposures on comparable cohorts or selected groups of people. The most common observational study designs are cohort studies and case–control studies

clinical trial: an experimental design for directly comparing clinical effects in human participants who are allocated to groups that receive different treatments – for example, to compare a drug treatment with a placebo. The most rigorous clinical trial design is the randomised controlled trial, in which participants are randomly allocated to the treatment groups

clinical trial


cloning (general): replicating and propagating the genetic makeup of an organism, either partially or completely. There are several different types of cloning (see below)

clone (cell culture): a population of cells derived from a single cell by cell division (mitosis). The clone is seen as a clump of cells in the cell culture dish. The cells in a cell culture clone are not necessarily identical

clone (plants): may refer to a cultured clone (as above), or to a group of plants derived by propagation from a single individual through cuttings or other asexual means

clone (bacterial): the unicellular progeny of a single bacterial cell. When grown on agar in petri dishes, bacterial clones form clusters (colonies)

molecular or DNA cloning: copying a particular sequence of DNA, and transferring it to a different cell (usually bacterial or yeast) using a DNA vector (usually a plasmid, phage or similar), where it is copied along with the rest of the cell’s DNA when the cells divide. This method can be used to produce large quantities of the product of the DNA sequence (eg to produce insulin). See also Recombinant DNA technology

cloning (animals): a type of reproduction in which the complete genotype of an animal is copied, generally by replacing the nuclear DNA of an egg cell from a host with the nuclear DNA of a body (somatic) cell from the donor organism (a process called somatic cell nuclear transfer). ‘Dolly’ the sheep was created in this way

therapeutic cloning: a method to obtain perfectly matched human embryonic stem cells from an individual. These cells have the potential to become tissue-specific cells that can be transplanted back into the individual to repair damaged cells or tissues without risk of rejection. The technique involves somatic cell nuclear transfer – the same technique that created Dolly the sheep – but the cloned egg cell containing the individual’s DNA is only allowed to form a small cell cluster (blastocyst), the inner layer of which is rich in stem cells. These stem cells are removed and used to create the specific cell type(s) required


Australia, which is a federation of the states and territories, is officially the Commonwealth of Australia. Commonwealth is often used to refer to national institutions such as the government and the parliament. However, because of the potential for confusion with the Commonwealth of Nations (the British Empire), Australian should generally be used in place of Commonwealth. References to legislation are the main context requiring use of Commonwealth, which should always have an initial capital:

the Australian Government
the Australian Parliament
the Commonwealth Environment Protection and Biodiversity Conservation Act 1990
the Environment Protection and Biodiversity Conservation Act 1990 (Cwlth)

communicable, contagious, infectious, infective, noncommunicable, transmissible

communicable disease, transmissible disease, infectious disease: a disease (such as one caused by a bacterium, virus or prion) that can spread from person to person, from animal to animal, between nonhuman animals and people, or from the environment to nonhuman animals or people, by direct or indirect means (eg via an insect vector). Communicable is more commonly used for human diseases than for animal diseases

contagious disease: a disease that spreads from person to person, from animal to animal, or between nonhuman animals and people, by direct contact with the infected individual or their secretions

infective animal or person: an animal or person who is at a stage of an infection at which they are able to spread the infection to others

noncommunicable: a disease or condition that is not spread among animals or humans, such as diabetes

transmissible: capable of being spread either directly (eg via contact or air) or indirectly (eg via a vector)

comparable, similar

comparable: able to be compared (ie having features in common), or worthy of comparison

The samples from the 2 locations were comparable because they were extracted using the same method.
Her intelligence is comparable to that of Einstein.

similar: resembling

The samples from the 2 locations gave similar results following analysis.

If two things closely resemble each other, it is preferable and less ambiguous to describe them as similar, rather than comparable.

compare to, compare with

compare with: consider similarities or differences between 2 or more items

They compared A with B.
Compared with last year, the results were disappointing.

compare to: liken to

Brown‘s results compare to Smith’s.

compare with

complement, compliment

complement (general): to go well together, to make complete

complement (biology): proteins in blood plasma that interact with antibodies to activate an immune response

compliment: to express praise (verb), or an expression of praise (noun)


compose, comprise, constitute

comprise: to consist of or contain

The genus comprises 8 species.

compose, constitute: to make up

Eight species constitute the genus.
The genus is composed of 8 species.


condition, disease, disorder, illness, syndrome

condition: a general term for diseases, lesions and disorders; often excludes mental health, where disorder is preferred (eg Diagnostic and statistical manual of mental disorders)

disease: a condition that impairs the normal function of a person, plant or animal. Diseases can be communicable (spread to a person from an animal, the environment or another person – eg measles, HIV, malaria, influenza) or noncommunicable (caused by environmental or genetic factors – eg cardiovascular diseases, cancer, diabetes, chronic respiratory diseases)

disorder: a synonym for disease (ie a functional abnormality), used for noninfectious conditions such as physical, metabolic or mental conditions; in mental health, mental disorder is preferred to mental illness

illness (sickness): a synonym for disease but often used to indicate the person’s experience of a disease (ie a person can have a disease without being ill or sick)

syndrome: the occurrence of several associated medical signs, symptoms or other characteristics (eg Down syndrome)

See also Disease names

congenital, genetic, genetics

congenital: a symptom or condition that one is born with (eg a congenital heart condition). Congenital conditions can be caused by either hereditary or environmental factors

genetic: relating to an organism’s DNA or genes (eg genetic code), or a mutation in an organism’s DNA or genes

genetics: the study of genes and heredity

consumer, patient

consumer: a person who is receiving health care assistance for any reason (ie including people who are not actually unwell, such as a woman having a baby or a person having a routine screening test). Changing use of patient to consumer also reflects a change in the relationship between people seeking health care advice or assistance and those providing the care, to one of a more equal partnership

patient: a person who is receiving health care. This term has the additional implied meaning that the person is unwell or sick; hence it has been replaced in many contexts with the term consumer

contamination, pollution

contamination: a hazardous substance such as a toxin, disease agent or radioactive material; exposure of an individual or the environment to such a substance; introduction of such a substance into water, air or soil at a concentration that makes the water, air or soil unsuitable for its intended use (also applies to surfaces of objects, buildings and products)

pollution: substances such as vehicle emissions and wastes that cause damage to the environment or adverse health effects; introduction of such substances to the environment

continual, continuous

continual: frequently repeated

People taking warfarin need continual monitoring.

continuous: continuing without a break

Nicotine patches allow continuous administration of nicotine.


convergence, homology, vestigiality

convergence: commonness in structures that have evolved independently. For example, the ability to fly is present in many types of animals that do not share a common evolutionary heritage

homology: commonness in structures or genes through evolution of species with a common ancestor. For example, wings in flying mammals, flippers in swimming mammals and forearms in primates are homologous

vestigiality: property of a trait that has been retained throughout evolution but has lost its function – for example, the coccyx (tailbone) in humans

criteria, criterion

Criteria is the plural of criterion.


cull, destroy, euthanase, kill, sacrifice, slaughter

These terms all refer to killing animals. Some have implications about the nature or purpose of the procedure:

  • euthanase: to subject to euthanasia – literally ‘a good death’; often used to emphasise that the animal was killed humanely
  • slaughter: often used to mean killing of an animal to produce meat for human or animal consumption.

Cull and sacrifice are best avoided because they are euphemisms. Of the other terms, the one chosen should be used consistently throughout a document to avoid confusion.

cultivar, hybrid, variety, plant variety

cultivar: a plant that has been bred for particular characteristics

hybrid: a plant that has been derived by cross-breeding of 2 plants of different species

variety: an international taxonomic rank below species for algae, fungi and plants

plant variety: a legal term for a cultivated plant that provides its breeder with some legal protection (so-called plant breeders’ rights). This term should not be confused with the international taxonomic rank of variety

data, datum

Data is the plural of datum. Datum is rarely used, and data should always be treated as a plural:

The data are     not     The data is


different from, different than, different to

These 3 expressions have the same meaning, but different from is the most common in Australian, British and American English. Different than is mainly seen in American English, and different to in British English. Different than and different to are often regarded as incorrect because things differ from each other (they don’t differ to each other or differ than each other). However, all 3 expressions have been used for centuries. Although all are acceptable, different from is regarded as less controversial and more correct.

dose, dosage, dosage form, dosage regimen

dose: the amount of substance administered at one time

The patient was given a dose of 500 mg of paracetamol.

dosage: the amount and rate of administration of a substance

The dosage was changed to 500 mg every 4 hours.

dosage form: the way in which a therapeutic agent is administered (eg a tablet, a capsule, a spray); also referred to as the formulation (especially in agriculture)

dosage regimen: the schedule of doses per unit of of time (eg the number and time of doses)

drug, medication, medicine

drug: a chemical substance that has a known effect in humans or animals. This term was previously used interchangeably with medicine; however, since drug is often associated with illicit substances, medicine is now the preferred term for many organisations (including the Therapeutic Goods Administration – the Australian Government agency responsible for the regulation of pharmaceuticals)

medication (noun): often used interchangeably with medicine (eg he took his medication). This term is favoured by health care professionals, particularly to distinguish it from the practice of medicine. Also the act of prescribing or administering a medicine (to medicate)

medicine: a pharmaceutical substance that has a specific effect in humans or animals, and is used to cure, alter or treat a disease or condition. Also, the practice of healing (eg they studied medicine)

due to


effectiveness, efficacy

effectiveness: capacity of an agent to achieve a specific outcome in practice (ie under ‘real world’ conditions)

efficacy: a measure of the probablility and intensity of beneficial effects under ideal conditions – for example, the ability of a therapeutic agent to improve a health outcome in a clinical trial

embryo, fetus

embryo: a multicellular diploid eukaryote in its earliest stage of development. In humans, this includes the developmental stages up to the end of the 7th week, after which the embryo is called a fetus

fetus: a developing vertebrate after the embryonic stage and before birth

enhance, improve, increase

Enhance should generally be avoided because it can have several meanings (improve, increase or intensify) and therefore can lead to ambiguity:

The plan was reviewed and improved to meet stakeholder expectations.
The plan was reviewed and enhanced to meet stakeholder expectations.


The program increases Australia’s capability to detect emerging diseases.
The program enhances Australia’s capability to detect emerging diseases.


few, fewer, less

The traditional rule is that fewer is used with nouns that can be counted:

fewer people    fewer samples

Less is used with nouns that cannot be counted:

less money    less oxygen

For percentages, use ‘fewer than’ if the thing being measured is a countable noun and ‘less than’ if it is an uncountable noun:

Fewer than 40% of people living in Geelong voted for the change.
Fewer than 80% of the apples are edible.
Less than 5% of the water in the dam was released after the downpour.
Women in the industry earn less than 90% of the wage received by men.


fish, fishes

Although often used interchangeably, in stricter biological usage, these 2 plural forms can have different meanings. Take care to maintain consistency:

  • fish: a group of fish of the same species
a school of fish [when all the fish are the same species]
  • fishes: several different species of fish
Sea fishes of South Australia [book title]

flammable, inflammable, nonflammable

flammable, inflammable: likely to burn easily. Flammable was introduced to avoid a false analogy between inflammable and words such as inactive, in which in means not. To avoid misinterpretation, always use flammable

nonflammable: not flammable

food allergy, food intolerance

food allergy (also called hypersensitivity): an abnormal response to a food that is triggered by the immune system

food intolerance: a response to food that is not associated with an immune response (even though the symptoms can resemble those of a food allergy) – for example, lactose intolerance is an inability to digest lactose in milk properly and is different from lactose allergy

food intolerance

forecast, prediction, projection

a statement of the likelihood of a future event under particular conditions that are variable or uncertain (eg if that happens, then this will follow)

gender, sex

sex: biological characteristics that identify individual organisms as male or female; also the act of sexual intercourse

gender (in relation to people): socially constructed roles, behaviours and activities associated with males and females, individually or in a group

The couple knew that the baby was female. [sex]
The girls laughed in a very feminine way. [gender]

Whereas the characteristics of sex do not differ substantially between cultures, the characteristics of gender may differ greatly between cultures and between individuals within a culture.

gender (in relation to language): term used in languages (eg French, German, Spanish) in which nouns can take a different definite article to distinguish them as masculine, feminine or neuter. This use of the word is much older than its use in relation to maleness and femaleness in people

gene technology, genetic engineering, genetic modification, gene therapy

gene technology, genetic engineering, genetic modification: these terms are generally interchangeable and are a part of biotechnology. Gene technology is the study of genes and gene expression; it can also mean taking advantage of natural variations in gene expression or manipulating gene expression for a certain purpose. Gene technology often involves cloning. See also cloning

gene therapy: a type of therapy in which a faulty gene is replaced with a working version, or a new gene is introduced to cure a condition or modify its effects

genetically modified organism, genetically modified product

genetically modified organism (GMO): a live organism whose genetic material has been altered using gene technology, or an organism that has inherited genetic traits from an organism that was modified using gene technology

genetically modified product: a thing (other than a GMO) that is derived or produced from a GMO – for example, flour, cotton or oil. Some genetically modified products have been approved for use as food or food additives, or as human or veterinary therapeutic agents. Food or other items containing such products are commonly referred to as GM foods or GM medicines. Use these terms with caution to avoid misunderstanding

genotype, phenotype

genotype: the alleles at a particular locus – that is, the genetic makeup (see also Mendelian genetics)

phenotype: the characteristics of a particular genotype that can be observed in an organism


green, sustainable

green: a colloquial term meaning ‘environmentally friendly’; confusing when used without definition, and best avoided in formal and technical writing

sustainable: refers to systems and processes that can continue functioning in the same way in the future while avoiding adverse effects, especially on the environment or natural resources – for example, sustainable agriculture uses systems that maintain or improve profitable production while conserving natural resources

heterozygous, homozygous

heterozygous: term used to describe alleles that are different at a particular locus within an organism

homozygous: term used to describe alleles that are the same at a particular locus within an organism



homogeneous, homogenous

homogeneous: composed of parts that are all of the same kind; not heterogeneous

homogenous: corresponding in structure because of a common origin (usually replaced by homologous)



hone, home

hone: to sharpen, to make more accurate, to improve through practice (eg to hone one’s skills)

home (as a verb): to return home

home in: to proceed towards a target

Hone is commonly confused with home in the phrase home in. It is not possible to hone in on a target.

hypothesis, law, theory

hypothesis: a tentative explanation for an observation or phenomenon that can be tested by further investigation. See also null hypothesis

theory: a hypothesis (or set of hypotheses) that has been repeatedly tested or is widely accepted. It often contains some explanatory content and can be used to make predictions about natural phenomena (eg Darwin’s theory of evolution, Newton’s theory of gravitation, Einstein’s theory of general relativity, the microorganism theory of infectious disease)

law: a principle presented as a bold statement that explains observations and has such good predictive power that it has been accepted to be universally true (eg Newton’s laws of motion). A law is different from a theory because it provides information on what will happen, not why it happens. Principle and law have similar meanings in this context, although a principle may have more explanatory content

immunise, immunity, inoculate, vaccinate

immunise: to deliberately administer an antigen to an individual in such a way that the individual develops an adaptive immune response to the antigen

immune: the state of being able to mount an adaptive immune response against an antigen that the individual has been exposed to before. An individual can become immune through immunisation or as a result of natural infection. Immunity can wane over time, so an individual may no longer be immune if they have been immunised in the past

inoculate: means the same as vaccinate and has been largely replaced by vaccinate when referring to human immunisation; still used in cell culture (for introducing cells into a new culture medium) and in animal research (for introducing a microorganism into a laboratory animal)

vaccinate: to administer antigenic material (a vaccine) to stimulate an individual’s immune response. The aim of vaccination is for the individual to be immunised (ie to become immune); however, an individual can be vaccinated but not become immune (eg as a result of vaccine failure)

impact, effect

impact (noun): a marked effect or influence

Floods can have a major impact on people living near the river.

In risk analysis, impact is used to describe the size of an effect associated with a risk event. High-impact events are more serious than low-impact events.

impact (verb): to have a noticeable effect on

The flood could impact several communities.

The use of impact as a verb has only recently become acceptable. It should not be overused and should be restricted to events that have large, significant or serious effects. Consider using affect or influence instead:

The flood could affect several communities

See also affect, effect

in vitro, in vivo

in vitro: in an artificial environment (Latin for in glass)

in vivo: in a living organism

in vivo

incidence, prevalence

incidence: the number of new cases (eg of disease) occurring in a population of stated size during a stated period of time

prevalence: the number of cases (eg of disease) existing in a population of stated size at a particular time


Inhibit can mean either ‘stop’ or ‘slow down’; care is therefore needed to avoid ambiguity.

interval, period

interval: a length of time between 2 specified points

period: a specified portion of time

isolation, quarantine

isolation: the separation of a person (or animal) who is ill from healthy people (or animals), to prevent the spread of disease

quarantine: the separation from other people (or animals) of a person (or animal) who has potentially been exposed to a communicable disease, to prevent the spread of disease. Importantly, the individual in quarantine does not yet have any signs or symptoms of the disease – that is, they are not currently ill with that disease. The word quarantine relates to the Italian word for forty – during the Black Plague in 14th-century Europe; ships were required to wait for 40 days before their passengers could come ashore. The period of quarantine differs for different diseases. Quarantine can also be applied to plants or objects such as vehicles


mass, weight

mass: the amount of matter that an object contains

weight: how strongly the mass is pulled by gravity (eg an astronaut is weightless in space but has the same mass as on Earth)


may be, maybe

may be (verb): could possibly be

The result may be surprising.

maybe (adverb): perhaps

Maybe the results will surprise you.


method, methodology

method: a process or technique

methodology: the general strategy of how a research project will be done, including identification of the methods to be used



molecular mass, molecular weight

molecular weight (MW): the ratio of the mass of a molecule to the standardised mass of an atom (note that MW does not take a unit because it is a ratio)

molecular mass: the mass of a substance divided by the amount of substance; usually expressed in daltons (Da) where 1 Da = 1 gram/mole

molecular weight


mutant, mutation

mutant: an organism carrying one or more mutations

mutation: an alteration in the primary sequence of the genetic material that can be mapped to a specific place (locus) on the DNA


natural, organic

natural: in the context of agriculture and chemical products, the terms natural and naturally derived should only be used to refer to substances and products that are 100% formed naturally, without the use of synthetic components or processes. See also green, sustainable

organic: in agriculture, refers to practices and products that do not use synthetic fertilisers or pesticides. In chemistry, an organic compound is any carbon compound, apart from a few types of compounds such as carbides, carbonates, simple oxides of carbon (eg CO and CO2) and cyanides

null hypothesis

A null hypothesis is the negative counterpart of a hypothesis. It is the hypothesis that the researcher seeks to reject so that the hypothesis of interest can be accepted.

optimal, optimum

Optimal is the adjective corresponding with optimum (a noun). However, optimum can also be used as an adjective:

The optimum conditions for plant growth include an adequate supply of micronutrients.



pathogen, pathology

pathogen: the causative agent of a communicable disease. For example, influenza (disease) is caused by influenza virus (pathogen); malaria (disease) is caused by species of Plasmodium (pathogen). It is a common mistake to use the term for the disease when you actually mean the pathogen, and vice versa:

He contracted measles     not     He contracted measles virus
The sample was tested for measles virus     not     The sample was tested for measles

pathology: the study of diseases; do not use to mean disease

Influenza is a disease     not     Influenza is a pathology



per cent, percentage

per cent: a term meaning units per 100

10 per cent or 10%

percentage: a statement of a quantity or rate expressed as the unit per cent

The results were expressed as percentages.

See also Percentages








principal, principle

principal (adjective): most important

principal (noun): a chief or head of a group (eg school principal)

principle (noun): a rule of conduct or a fundamental truth

See also hypothesis, law, theory



Proof is a dangerous word in the context of science because its common, scientific, mathematical and legal meanings are all different. This has been used to discredit scientists when they are asked, for example, to ‘prove’ evolutionary theory, that genetically modified foods can do no harm or that something else is irrefutably true. Such demands are at odds with the nature and process of science, which can disprove things that are untrue but be unable (philosophically) to prove them. Science is said to support propositions with varying degrees of probability (see significant, statistically significant), which may be so consistently high that the propositions can be relied on. Safer alternatives to proof that are often used include supported, established and demonstrated:

Scientists have demonstrated that Ebola is hard to contract.
Theories of global warming are well established in science.
Clinical trials have strongly supported the effectiveness of quinine.

Despite the above, proof and prove have technical meanings within science and technology – for example, ‘proving’ cannons to show that they are functional and the ‘proof’ of spirits of a certain strength.

proof (mathematics): a statement shown to be valid by logical argument

proof (legal): that which has been declared to be so by a jury, judge or legal authority


race (human)

Race is a biological term that is used to describe groups of animals (including humans) or sometimes plants. It was once believed that there were several races of humans, but modern genetics has shown this not to be the case. In the meantime, race and racist have become entrenched in common usage, no longer having any scientific validity, but being used ambiguously to suggest a range of features, from nationality and skin colour to religion and parentage. Although race remains a valid term in biology, it is an invalid term with which to describe human variation. Racist is similarly ambiguous, its meaning being more accurately embraced by terms such as xenophobe or bigot.

rainfall, rainwater, runoff, stormwater

rainfall: the amount (usually measured in millimetres) of rain that falls in a given period and area

rainwater: water that has fallen as rain

runoff: rainwater that is not absorbed into soil but flows on the surface as streams

stormwater: water that produces a sudden, large runoff after a storm

regime, regimen

Interchangeable terms from the same Latin root meaning a plan, system or routine. Regime can also relate to government; regimen is more common in health and medical writing.



sensitivity, specificity

sensitivity: the proportion of truly positive units that are correctly identified as positive by a test

specificity: the proportion of truly negative units that are correctly identified as negative by a test

sewage, sewerage

sewage: waste materials that pass through sewers

sewerage: the system of drains that carries sewage

Sewage system and sewerage system are both acceptable.



sign, symptom

sign: evidence of disease that can be recognised by someone other than the patient. For example, a rash, diarrhoea and fever are signs because they can be detected by another person

symptom: evidence of disease that can only be reported by the patient. For example, a headache, nausea and muscle aches are symptoms because they can only be experienced by the patient; other people can only know about them if told by the patient

significant, statistically significant

In science writing, significant should be used with care because it can indicate either statistical significance or a quality of importance, leading to ambiguity:

There was a significant difference between the 2 populations in their racial makeup. [It is not clear whether this means an obvious and important difference or a difference that is statistically significant.]

Alternative terms to indicate nonstatistical significance include substantial, important, major and valuable. See also proof


solute, solution, solvent

solute: a substance that is dissolved in a solvent to produce a solution

solution: a homogeneous mixture that is produced when a solute is dissolved in a solvent

solvent: a substance in which a solute is dissolved to produce a solution



statistically significant



that, which

that: used for defining (restrictive) clauses (information that defines the subject and cannot be omitted from a sentence without greatly changing the meaning)

The residues that were detected in beef were at very high levels. [Omitting the italicised words (a restrictive clause) would change the meaning of the sentence.]

which: used for nondefining (nonrestrictive) clauses (incidental information that does not significantly limit the meaning of the principal clause)

CFZ residues, which have been detected in beef, are not permitted in human food. [The italicised words (a nonrestrictive clause) may be omitted without affecting the meaning of the sentence.]

use, utilise

Utilise is usually just a more pompous way of saying use, and should be avoided.

Exceptions include terms such as feed utilisation (by livestock), which refers to the efficiency with which livestock convert feed into body mass, or health technology utilisation, which refers to the number of uses of a health technology in a specified period.




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