forwarn

Inherited from Middle English forwernen inherited from Old English forwærnan inherited from Proto-Germanic *fra- (for-, fully, away, prefix meaning completely) derived from Proto-Indo-European *wer- (heed, cover, defend, protect, burn, close, save, bend, turn, guard, rope, squirrel, envelop, boil, crook, notice, give heed, string, watch, speak, note, high, twist, perceive, tie, sense, blister, bond, blacken, shut, be wary, shelter, bind with a rope, highland, sketch an outline, become aware, take heed, stoat, make, cut, look out for, raised area, be aware, be watchful, tear, pay attention, scratch, observe, tuber, lump, work, be careful) prefix from English warn (refuse, deny, forbid).

English