1610s, "unfit, improper," from Middle English ungeinliche, from ungein (late 14c.) "inconvenient, disagreeable, troublesome," from un- (1) "not" + gein "kind, helpful; reliable; beneficial; suitable, appropriate; convenient," from Old Norse gegn "straight, direct, helpful," from Proto-Germanic *gagina "against" (see again). Old English had ungænge "useless, vain."
