noun suffix or pronoun suffix
Etymology: Middle English -es, -s, genitive singular ending, from Old English -es; akin to Old High German -es, genitive singular ending, Greek -oio, -ou, Sanskrit -asya
— used to form the possessive of singular nouns <boy's>, of plural nouns not ending in s <children's>, of some pronouns <anyone's>, and of word groups functioning as nouns <the man in the corner's hat> or pronouns <someone else's>
New Collegiate Dictionary. 2001.