early 14c., from L. contractus, pp. of contrahere "to draw together," metaphorically, "to make a bargain," from com- "together" + trahere "to draw" (see tract (1)). Noun came first, then verb and variant meaning "become narrowed, get smaller," especially of a withered limb (both 17c.). U.S. underworld slang sense of "arrangement to kill someone" first recorded 1940. Related: Contracting (1580s).