late 15c., mappe "bundle of coarse yarn, cloth, etc., fastened to the end of a stick for cleaning or spreading pitch on a ship's decks," perhaps from Walloon (French) mappe "napkin," from Latin mappa "napkin" (see map (n.)). Modern spelling by 1660s. General sense, of such an implement for cleaning floors, windows, etc., is from 1610s. Of smaller utensils of the same sort used for cleaning dishes, etc., by 1869. Of anything having the shape or appearance of a mop (especially hair), by 1847. Grose ["Dictionary of the Vulgar Tongue," 1788] has mopsqueezer "A maid servant, particularly a housemaid."
also cleanup, 1856, "act of cleaning up, a general cleaning," from clean + up. Meaning "a profit" is recorded from 1878. Verbal phrase clean up "make a large profit" is from 1929. The adjective, in the baseball sense, is recorded by 1910 in reference to the hitter who bats fourth in the lineup: His job is to drive in runs by scoring the players who hit before him and thus "clean up" the bases.
"done by automatic equipment," 1952, American English, adjective based on automation.