1580s, from Greek elephantos, genitive of elephas "elephant" (see elephant) + -iasis "pathological or morbid condition." It refers to two diseases, one characterized by thickening of a body part (E. Arabum), the other, older meaning is "disease characterized by skin resembling an elephant's" (E. Græcorum, also called Egyptian leprosy). In Middle English, elephancy (late 14c.).