1530s, "waste discharged from the body," from Latin excrementum, from stem of excretus, past participle of excernere "to sift out, discharge," from ex- "out" (see ex-) + cernere "sift, separate" (see crisis). Originally any bodily secretion, especially from the bowels; exclusive sense of "feces" is since mid-18c. Related: Excremental; excrementitious.