late Old English wimman (plural wimmen), literally "woman-man," alteration of wifman (plural wifmen), a compound of wif "woman" (see wife) + man "human being" (in Old English used in reference to both sexes; see man (n.)). Cf. Dutch vrouwmens "wife," literally "woman-man."
The formation is peculiar to English and Dutch. Replaced older Old English wif and quean as the word for "female human being." The pronunciation of the singular altered in Middle English by the rounding influence of -w-; the plural retains the original vowel. Meaning "wife," now largely restricted to U.S. dialectal use, is attested from mid-15c. Women's liberation is attested from 1966; women's rights is from 1840, with an isolated example in 1630s.