ptomaine (n.)

1880, from Italian ptomaina, coined by Professor Francesco Selmi of Bologna, 1878, from Greek ptoma "corpse," on notion of poison produced in decaying matter. Greek ptoma is literally "a fall, a falling," via the notion of "fallen thing, fallen body;" nominal derivative of piptein "to fall" (from PIE *pi-pt-, reduplicated form of root *pet- "to rush; to fly"). Incorrectly formed, and Selmi is roundly scolded for it in OED, which says proper Greek would be *ptomatine.