Acronyms and initialisms

Acronyms and initialisms both consist of a string of letters that are the first letters of each word of the title or phrase they refer to. Each letter is usually capitalised. The term acronym is often used to cover both acronyms and initialisms, but there is a difference between them.

The letters of an acronym can be pronounced as a single word:

ANZAAS     AWOL     DFAT     TAFE     

The letters of an initialism are pronounced one by one, as separate syllables:

CEO     HSC     MBA     NHMRC     PTO     YMCA

A few of these shortened forms may be pronounced either way – for example, WHO (World Health Organization). They may thus be treated as either acronyms or initialisms.

Shortened forms that have the same spelling as normal words (eg WHO, POW, PIN) can raise accessibility issues because of the way they are treated by screen readers. For web writing, it is a good idea to define terms on every webpage because of this issue.

Neither acronyms nor initialisms are punctuated with full stops. Add an s, without an apostrophe, for acronyms and initialisms that take a plural:

chief executive officers (CEOs)   not   chief executive officers (CEO’s)

This section also covers:

Using acronyms and initialisms

Before an acronym or initialism is used in the text, give the full title or phrase, followed by the shortened form in brackets. After this, use the shortened form only, unless there is a good reason to repeat the full title or phrase in a new section or chapter – for example, if many pages separate the previous use of the shortened form from the next.

As a general rule, if an acronym or initialism would be used just once or twice in the text, write the term in full rather than introducing the shortened form.

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Capitalisation of acronyms and initialisms

The names of organisations take capital letters in both their full and shortened forms:

Australian Securities & Investments Commission (ASIC)

Organisation for Economic Co-operation and Development (OECD)

United Nations Educational, Scientific and Cultural Organization (UNESCO)

But other terms and phrases use lower case when spelled out in full, even though their acronym or initialism takes capitals:

gross domestic product (GDP)

maximum residue limit (MRL)

nongovernment organisation (NGO)

Some acronyms have become so well established that they do not take full capitals, and do not need to be defined or included in a list of shortened forms:

Anzac (Australian and New Zealand Army Corps)

laser (light amplification by stimulated emission of radiation)

Qantas (Queensland and Northern Territory Aerial Services)

scuba (self-contained underwater breathing apparatus)

sonar (sound navigation ranging)

If a sentence opens with a shortened form that starts with a lower-case letter (eg a technical term such as mRNA), rewrite the sentence so that the shortened form does not appear at the beginning of the sentence, or write the term in full:

mRNA moves information contained in DNA to the translation machinery.
The role of mRNA is to move the information contained in DNA to the translation machinery.
Messenger RNA moves information contained in DNA to the translation machinery.

For brand names that usually start with a lower-case letter (eg eBay, iPhone), capitalise the first letter if the word occurs at the beginning of a sentence or rewrite the sentence so that the shortened form does not appear at the beginning:

EBay is a sales platform for both personal and commercial sales.
Both personal and commercial sales can be made through eBay.

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Articles with acronyms and initialisms

In running text, you will often need to use articles (a, an or the) before an acronym or initialism.


When a or an is required before an acronym, use the one that sounds correct when reading the text aloud. This means going by the sound at the start of the word, rather than whether it is written as a vowel or consonant:

APACE is an NGO working in the Pacific. [N is pronounced en – starting with a vowel sound]

7.30 is an ABC program. [A is pronounced as a vowel]

A UNICEF program … [U is pronounced yu – starting with a consonant]


In general, use the with initialisms, but not with acronyms:

The RSPCA met with PETA to discuss the issue.

Use the article the before initialisms used as nouns, but not when they are used as modifiers before a noun:

The RSPCA supported the report.

RSPCA raffles are held regularly.

Some house styles tend not to use the with initialisms for government departments, but do use it for government agencies:

She worked as a policy officer at PM&C. Before that, she was a statistician at the ABS.
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Very well known acronyms and initialisms

Acronyms and initialisms that are more familiar to your readership than the full title or phrase need not be written out in full on first mention. However, they should be included in the publication’s list of shortened forms (see Lists of shortened forms).

Familiar acronyms and initialisms may include:

ABC (Australian Broadcasting Corporation)

AIDS (acquired immunodeficiency syndrome)

DNA (deoxyribonucleic acid)

GPS (global positioning system)

HIV (human immunodeficiency virus)

HMAS (Her Majesty’s Australian ship)

IQ (intelligence quotient)

ISBN (International Standard Book Number)

SBS (Special Broadcasting Service)

Alternatively, for familiar acronyms or initialisms, you can reverse the order by using the shortened form before the full term:

Watson and Crick won a Nobel Prize for their work on the structure of DNA (deoxyribonucleic acid).

Think about your readership when deciding whether to spell out terms. The following examples would be well known to particular readerships, and may not need to be spelled out if you know your audience will understand them:

AFL (Australian Football League) [sports readerships]

CI (confidence interval) [statistically trained readers]

CSIRO (Commonwealth Scientific and Industrial Research Organisation) [Australian readers]

DIY (do it yourself) [home-handy people]

PCR (polymerase chain reaction) [molecular biologists]

Terms associated with established digital technologies do not need to be spelled out in full in the body of the publication or included in the list of shortened forms:

CD (compact disc)

DVD (digital versatile disc)

HTML (hypertext markup language)

JPEG (Joint Photographic Experts Group)

SMS (short messaging service)

URL (uniform resource locator)

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Organisation names that have changed over time

The official names of some organisations now consist of just the shortened form. The original name that was the basis for the shortened form is never used; it should not be included in the text or in the list of shortened forms:

AFS [formerly American Field Service]

KPMG [stands for Klynveld Peat Marwick Goerdeler]

RSPCA Australia [formerly Royal Society for the Prevention of Cruelty to Animals (Australia)]

UNICEF [formerly United Nations International Children’s Emergency Fund]

The shortened form for some other organisation names no longer fully reflects the original name, or reflects the organisation’s name in another language; these should be spelled out at first use, as usual:

United Nations Population Fund (UNFPA) [formerly United Nations Fund for Population Activities]

World Organisation for Animal Health (OIE) [Office International des Epizooties, in French]

Always check each organisation’s preferred official name and shortened form on their website or in their publications.

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