O.E.
wærloga "traitor, liar, enemy," from
wær "faith, a compact" (cf. O.H.G.
wara "truth," O.N.
varar "solemn promise, vow;" see
very; cf. also
Varangian) + agent noun related to
leogan "to lie" (see
lie (v.1)). Original primary sense seems to have been "oath-breaker;" given special application to the devil (c.1000), but also used of giants and cannibals. Meaning "one in league with the devil" is recorded from c.1300. Ending in
-ck and meaning "male equivalent of
witch" (1568) are from Scottish.