genitive plural of monstrum
Conclave Monstrōrum (Latin) - Conclave of Monsters
~ Early 14c., "malformed animal or human, creature afflicted with a birth defect,"
~ from Old French monstre, mostre "monster, monstrosity" (12c.), and
~ directly from Latin monstrum "divine omen, portent, sign; abnormal shape; monster, monstrosity," figuratively "repulsive character, object of dread, awful deed, abomination,"
~ from root of monere "warn" (see monitor (n.)). Abnormal or prodigious animals were regarded as signs or omens of impending evil.
~ Extended by late 14c. to imaginary animals composed of parts of creatures (centaur, griffin, etc.).
~ Meaning "animal of vast size" is from 1520s;
~ sense of "person of inhuman cruelty or wickedness" is from 1550s.
~ As an adjective, "of extraordinary size," from 1837.
~ In Old English, the monster Grendel was an aglæca, a word related to aglæc "calamity, terror, distress, oppression."