Sep 5, 2025 whack ˈ(h)wak 1 syllable uncommon ‹ verb.to strike with a smart or resounding blow whack the ball verb.to cut with or as if with a whack: chop verb.to get the better of: defeat noun.a smart or resounding blow; also: the sound of or as if of such a blow take a whack at itborrowed $50 all at one whack noun.a critical attack noun.portion, share › Origin probably imitative of the sound of a blow.