n., v., & adv.
n. 1 a sharp slap or blow esp. with the palm of the hand or a flat object. 2 a hard hit at cricket etc. 3 a loud kiss (gave her a hearty smack). 4 a loud sharp sound (heard the smack as it hit the floor).
v. 1 tr. strike with the open hand etc. 2 tr. part (one's lips) noisily in eager anticipation or enjoyment of food or another delight. 3 tr. crack (a whip). 4 tr. & intr. move, hit, etc., with a smack.
adv. colloq. 1 with a smack. 2 suddenly; directly; violently (landed smack on my desk). 3 exactly (hit it smack in the centre). have a smack at colloq. make an attempt, attack, etc., at. a smack in the eye (or face) colloq. a rebuff; a setback.
[ MDu. smack(en) of imit. orig. ]