late 13c., wenche
"girl or young woman," shortened from wenchel
"child" (12c.), from O.E. wencel
, probably related to wancol
"unsteady, fickle, weak," and cognate with O.N. vakr
"child, weak person," O.H.G. wanchal
"fickle." The word degenerated through being used in ref. to servant girls, and by mid-14c. was being used in a sense of "woman of loose morals, mistress." The verb meaning "to associate with common women" is from 1590s.
"The wenche is nat dead, but slepith." [Wyclif, Matt. ix.24, c.1380]