Slap  —v. (-pp-) 1 strike with the palm or a flat object, or so as to make a similar noise. 2 lay forcefully (slapped it down). 3 put hastily or carelessly (slap paint on). 4 (often foll. By down) colloq. Reprimand or snub. —n. 1 blow with the palm or a flat object. 2 slapping sound. —adv. Suddenly, fully, directly (ran slap into him). [low german, imitative]