What is the possessive of a noun ending in ‑s? Are these both right, or is the second one wrong?

  1. the boys' books

  2. the boss' car


Your example sentences confuse two different problems.

For nouns that are plural (such as "boys"), the possessive is formed in writing by adding an apostrophe after the plural -s. This is pronounced the same as the plural and the singular possessive:

The boys' books [boys' sounds like boys]

For singular nouns that end in -s, the possessive is formed by adding -'s, just as with other nouns. This is pronounced as if the spelling were es:

The boss's car [boss's sounds like bosses]

There is a partial exception for proper names that end in s. These names sometimes form their possessive by simply adding an apostrophe, and without changing their pronunciation:

Confucius' sayings

Jesus' teachings

However, this doesn't apply if the name ends with a letter other than s, even if it's pronounced with an s. These names form their possessive as normal:

Marx's theories

In the opposite case of a name which ends in a silent s, the possessive is usually formed by adding an apostrophe in writing, but the apostrophe causes the silent s to be pronounced:

Camus' novels [the final -s in Camus is not silent here]

  • 4
    +1, I hadn't thought about the implications of the proper name exception when used with a silent final s. – cori Aug 16 '10 at 22:08
  • 11
    +1, but I'll note that there exist style guides which follow the following simplistic rule: if a singular noun ends with an s, just add “'s”, regardless of whether it's a proper noun or how it's pronounced. I like the simplicity of this rule. – ShreevatsaR Aug 16 '10 at 22:32
  • 3
    Do you have a source on this with proper names not needing an extra s? I am fairly certain it should still be Confucius's sayings, Jesus's teachings, and Camus's novels, with the first s still silent in the last case. – StrixVaria Aug 19 '10 at 16:13
  • 3
    @FumbleFingers But "mistresses" is already plural and wouldn't get the extra s after the apostrophe anyway. – StrixVaria May 26 '11 at 1:23
  • 3
    Do you have any authoritative references? I'm not asking because I don't believe you. I'm asking because when the question comes up I can't say "because some guy on the internet said so", not even if said guy got 60 upvotes. – Szabolcs Feb 26 '15 at 18:08

On singular nouns that end with an "s" or "z" sound, Wikipedia has a say. According to the article, there is no hard and fast rule on this one and different "authorities" prefer different styles.

See also St. James's park and St. James' park.

protected by user2683 Mar 29 '12 at 0:42

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