Apostrophes ’

The first use of an apostrophe is easy enough. When shortening two words into one contraction, add an apostrophe to show where the letters are missing.

But even here there is a common trap, because ‘its' ‘your’ and ‘their’ (without apostrophes) are possessive pronouns and do not take an apostrophe. See below for more on that exception. 

To show possession or ownership, most words will either:

• add an apostrophe and then the letter ‘s’ (for singular words)
• add an apostrophe after the ‘s’ (for plural words).

The 2 areas that can create uncertainty are:

• singular nouns that already end in ‘s’
• irregular words that form a plural without an ‘s’.

Singular nouns

Let’s take the singular forms first:

Note that even when the singular noun ends in ‘s’ (usually a name), you can simply add an apostrophe and ’s’ at the end to be consistent with the general rule. Too many style guides have gotten tangled up in exceptions where they recommend not adding an ‘s’ if it involves a major historical figure (the Jesus’ rule) or it sounds awkward (the Menzies’ rule). The ASG recommends keeping it simple and consistent: hence ‘James’s book’.

Plural nouns

When a noun has 2 or more owners, you usually add an apostrophe after the final ‘s’:

But watch out for irregular plurals that don’t end in ‘s’. These follow the singular possessive approach:

Shortened forms

Follow the same rules for acronyms and initialisms. But remember that sometimes the shortened form serves as an adjective, not a possessive, and does not take an apostrophe or ‘s’.

Perhaps the biggest apostrophe brain teaser occurs in government organisations whose title ends in a plural noun that itself ends in ‘s’. How do you indicate possession in both the full title and the acronym?

While we mostly use apostrophes to show possession, doing so for possessive pronouns would give us the same form as we use for a contraction. Possessive pronouns such as ‘theirs’, ‘his’ and ‘hers’ are therefore the main exception to a word indicating possession taking an apostrophe.

Take extra care with the pronoun ‘its’ (owned by it), which doesn’t need an apostrophe. Even when you know the rule, it is easy to write the contraction ‘it’s’ (short for ‘it is’) simply because we use it so often. And a spell check may not pick it up.

When we are not thinking consciously about apostrophe rules and exceptions, it is easy for our brains to put apostrophes in words that don’t need them – simply because some of the rules and cases appear to clash.

Never add apostrophes to regular plural nouns that don’t own anything, even when the ‘s’ comes after a vowel, a number or a shortened form.

And don’t add apostrophes to any Australian place names, or to organisation names unless the organisation itself uses one.

The removal of apostrophes from place names is one of the features of Australian style – a decision that stems back to the 1960s. Not only is this simpler, but it is technically justified because the words in place names are descriptive more than possessive. The ‘King’ does not actually own ‘Kings Cross’. In countries such as the United Kingdom, there is an inconsistent mix with some names taking apostrophes and some not.