adj. 1. a. Shockingly hideous or frightful in appearance. b. Of or resembling a fabulous monster. 2. Exceptionally large; enormous: a monstrous tidal wave. 3. Extremely immoral or cruel: a monstrous dictator; monstrous behavior. 4. Archaic Deviating greatly from the norm in appearance or structure; abnormal. [Middle English, from Old French monstruos, from Latin mōnstruōsus, from mōnstrum, portent, monster; see MONSTER.] monstrous·ly adv. monstrous·ness n. |
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