abominable:  The Latin original of this word meant ‘shun as an evil omen’. The prefix ab- ‘away’ was added to ōmen (source of English omen) to produce the verb abōminārī. From this was created the adjective abōminābilis, which reached English via Old French. From the 14th to the 17th century there was a general misapprehension that abominable was derived from Latin ab hominem ‘away from man’, hence ‘beastly, unnatural’.
This piece of fanciful folk etymology not only perpetuated the erroneous spelling abhominable throughout this period, but also seems to have contributed significantly to making the adjective much more strongly condemnatory. => omen
mid-14c., from Old French abominable (12c.) and directly from Late Latin abominabilis "deserving abhorrence," from stem of Latin abominari "deplore as an evil omen" (see abomination). Sometimes misdivided in earlier centuries as a bominable. Also often abhominable 14c.-17c. Related: Abominably.