Plural nouns refer to more than one person or thing, for example 'brothers'. To show possession when the noun is plural and already ends in 's', you just add an apostrophe to the end of the word. You don't need to add an extra 's'. For example: The brothers' feet were muddy. The cats' fur is very fluffy.

Apostrophe after “s” for possession with plural nouns Plural nouns that end in “s” (most plural nouns) form the possessive with an apostrophe after the “s,” without adding a second “s.” For example, to describe the roofs of multiple houses, you would write “the houses’ roofs” (“the house’s roofs” would refer to multiple roofs on one house).

Most plural nouns already end in s. In this case, to indicate possession, add only an apostrophe to the end of the word. This also applies to words where the singular and the plural take the same form.

To show possession using an apostrophe, add ’s for individuals (“Smith’s car”) and just the apostrophe after the s for plurals (“the Smiths’ car,” “the Martinezes’ dog”). By convention, names from classical mythology and the Bible ending in s show possession with the apostrophe only (“Jesus’ teachings”).