abominable (adj.)
mid-14c., "exciting disgust or loathing, morally detestable," from Old French abominable (12c.) and directly from Late Latin abominabilis "deserving abhorrence," from stem of Latin abominari "deplore (as an evil omen)," hence, generally, "detest, execrate, deprecate," from ab "off, away from" (see ab-) + omin-, stem of omen (see omen).

The more common Middle English form was abhominable, which persisted into 17c.; it is a folk-etymology, as if from Latin ab homine "away from man" (thus "beastly"). In early Modern English sometimes misdivided as a bominable. Related: Abominably; abominableness. Abominable snowman (1921) translates Tibetan meetaoh kangmi.