to hit something hard and noisily with a sharp blow.
Origin uncertain, possibly imitative in nature (onomatopoeia), first recorded in English around 1600s. The word mimics the sound of impact. Related to similar impact words across Germanic languages.
The word 'whack' is onomatopoeia—it literally sounds like the action it describes! Your brain processes the sound /wæk/ and instantly 'hears' a hard hit, which is why this word feels so satisfying to say.
Complete word intelligence in one call. Free tier — 50 lookups/day.