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.