also pullback, 1660s, "act or action of pulling back," from the verbal phrase; see pull (v.) + back (adv.). From 1951 in the military sense of "orderly withdrawal of troops."
also canvasback, 1785 as a type of North American duck, so called for the color of the back. Earlier as an adjective for a type of garment made of expensive stuff in front and cheap canvas in the back (c. 1600); from canvas (n.) + back (n.).