Word Origin & History
suffix forming the possessive case of most Mod.Eng. nouns, was gradually extended in M.E. from O.E. -es, the most common genitive inflection of masc. and neut. nouns (cf. dæg "day," gen. dæges "day's"). But O.E. also had genitives in -e, -re, -an as well as "mutation-genitives" (cf. boc "book,"
plural bec), and the -es form was never used in plural (where -a, -ra, -na prevailed), thus avoiding the ambiguity of words like kings'. As a suffix forming some adverbs, it represents the gen. sing. ending of O.E. masc. and neuter nouns and some adjectives.