Word Origin & History
"defecate" 1846 (v.), 1898 (n.), from one of a cluster of words generally applied to things cast off or discarded (e.g. "weeds growing among corn" (1425), "residue from renderings" (1490s), 18c. underworld slang for "money," and in Shropshire, "dregs of beer or ale"), all probably from M.E. crappe "grain
that was trodden underfoot in a barn, chaff" (c.1440), from M.Fr. crape "siftings," from O.Fr. crappe, from M.L. crappa, crapinum "chaff." Sense of "rubbish, nonsense" also first recorded 1898. Despite folk etymology insistence, not from Thomas Crapper (1837-1910) who was, however, a busy plumber and may have had some minor role in the development of modern toilets. The name Crapper is a northern form of Cropper (attested from 1221), an occupational surname, obviously, but the exact reference is unclear.
1843, Amer. Eng., unrelated to the term for excrement, from Louisiana Fr. craps, from Fr., corruption of Eng. crabs (see crab
), 18c. slang for "a throw of two or three," which is perhaps from the crab sense in crab apple.