n. 1 an imaginary creature, usu. large and frightening, compounded of incongruous elements. 2 an inhumanly cruel or wicked person. 3 a misshapen animal or plant. 4 a large hideous animal or thing (e.g. a building). 5 (attrib.) huge; extremely large of its kind.
[ ME f. OF monstre f. L monstrum portent, monster f. monere warn ]