Word Origin & History
1540, "soft material for padding or stuffing," of uncertain origin, and the different meanings may represent more than one source. Among the possible connections are M.L. wadda, Du. watten, and M.E. wadmal (1392) "woolen cloth," which seems to be from O.N. vaðmal "a woolen fabric of Scandinavia,"
probably from vað "cloth" + mal "measure." The meaning "bundle of currency" is Amer.Eng., 1778. The verb is first recorded 1579. To shoot (one's) wad "do all one can do" is recorded from 1914. The immediate source of the expression probably is the noun sense of "disk of cloth used to hold powder and shot in place in a gun." Wad in slang sense of "a load of semen" is attested from 1920s, and the expression now often is felt in this sense. As a suffix, -wad in 1980s joined -bag, -ball, -head in combinations meaning "disgusting or unpleasant person."