Apostrophes showing relationships between nouns

Apostrophes can express different relationships between 2 successive nouns:

  • possession – when the first noun or name owns the second, or the second noun belongs to the first
  • attribution – when the first noun or name is the site or source of the second
  • expressions of time – when the first noun is a single unit of time that defines the scope of the second noun.

The way in which the apostrophe is used depends on whether the first noun is singular or plural.

This section covers use of apostrophes in:

Singular nouns

To show possession with singular nouns (common or proper) and proper names, add an apostrophe followed by s:

a dog’s bone [the bone belonging to the dog]     the truck’s headlights     Dr Smith’s car     Lady Mary’s smile    

Do the same to show attribution:

Australia’s population [the population of Australia]     Earth’s circumference     Japan’s politics
Sydney’s traffic     Plato’s philosophy     the Royal Commission’s recommendations

And follow the same rule for singular nouns that already end in s:

the boss’s job description     the glass’s shape     James’s car     Tacitus’s Histories     Jesus’s teachings
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Plural nouns

To show possession or attribution for plural nouns ending in -s or -es, add an apostrophe only:

cactuses’ spines     employees’ wages     students’ grades     state governments’ response

For the plural possessives of names that already end in s, make the noun plural in the standard way, then follow with an apostrophe:

the Joneses’ house     the Thomases’ children
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Expressions of time

Use apostrophes in expressions that are based on singular units of time:

an hour’s delay     in 1 day’s time     a month’s salary     next week’s plan 

but not in expressions of plural time periods (see When not to use apostrophes).

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