Possible Duplicate:
What is the correct possessive for nouns ending in s?

Before you vote to close as a duplicate, note that these two questions deal with similar issues to this, but none of them address all three criteria of this question:

  • The singular already ends with an s.
  • I am dealing with multiple of the thing.
  • I want the possessive of all of them in general.

The singular is class, and the plural is classes. The singular possessive is class's (as addressed here).

What is the plural possessive? Is it classes's, or classes'?

  • I suspect there are few, if any, cases where of the classes would not be possible as a way of avoiding the successive sibilants of classes's. Oct 3, 2011 at 6:40
  • 1
    It's not a dupe because of "boss" because "boss" is not plural. Oct 3, 2011 at 11:23
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    @PeterShor He could comment under JSBangs answer asking about the plural of boss. The difference is not enough to ask a different question, it can simply be asked under that answer as a comment. Anyway, the closing works with votes. If not enough people will agree with me, the question will stay open.
    – Alenanno
    Oct 3, 2011 at 11:44
  • @BarrieEngland The words classes's and dogs's are not correct possessives of plurals in English. To form the plural of a word that is pluralized by adding s, you simply add an apostrophe to the plural form. For regular English plurals, the plural, the possessive, and the possessive of the plural, are all pronounced exactly the same; for dog, these are dogs, dog's, and dogs', respectively. Oct 3, 2011 at 12:30
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    I suppose that if classes is no different to boss, then yes, that answer does address this question, but I wasn't sure if the fact that class has already had an es tacked on the end would change things at all. Either way, 9 people so far have found this question and one of its answers useful enough to upvote. Oct 3, 2011 at 22:34

2 Answers 2


It is classes', which sounds the same as the singular class's.

I would have thought this was a general rule for plural nouns ending -s', -es' or -ies'.

  • 1
    Exceptions are geese's, mice's, and lice's. Oct 3, 2011 at 11:17
  • @Peter: geese, mice and lice do not end with s in the plural (nor do children or people).
    – Henry
    Oct 3, 2011 at 14:38
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    They end with an 's' sound. If you want an exception that actually ends with an 's', bass (the fish) is one. Plural: bass. Plural possessive: bass's. It rhymes with classes. Oct 3, 2011 at 15:13

Here's the rule: For plural nouns that end in S, only add the apostrophe. For singular nouns, add apostrophe-S.

This gives you the following. The class (singular noun): The class's project. The classes (plural noun): The classes' project.

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