insect order having the wings sheathed by hardened shells, 1763, from Modern Latin, from Greek koleopteros, literally "sheath-wing," used by Aristotle to describe beetles, from koleos "sheath" (from PIE root *kel- (1) "to cover, conceal, save") + pteron "wing" (from PIE root *pet- "to rush, to fly"). Related: Coleopterous; coleopteran; coleopteral.