1. Something of unnatural size, shape, or quality; a prodigy; an enormity; a marvel. A monster or marvel. (Chaucer)
2. Specifically, an animal or plant departing greatly from the usual type, as by having too many limbs.
3. Any thing or person of unnatural or excessive ugliness, deformity, wickedness, or cruelty.
Origin: OE. Monstre, F. Monstre, fr. L. Monstrum, orig, a divine omen, indicating misfortune; akin of monstrare to show, point out, indicate, and monere to warn. See Monition, and cf. Demonstrate, Muster.