Emily Dickinson Lexicon

MON'STER, a. [L. monstrum, from monstro, to show. So we say in English, a sight. See Muster.]

1. An animal produced with a shape or with parts that are not natural, as when the body is ill formed or distorted, or the limbs too few or too many, or when any part is extravagantly out of proportion, either through defect or excess.
2. Any unnatural production; something greatly deformed. Monsters are common in the vegetable kingdom. Encyc.
3. A person so wicked as to appear horrible; one unnaturally wicked or mischievous. So a parricide is called a monster.