whack
v.v. to hit something or someone very hard. It is a casual word for a strong, noisy strike.
v. to strike with a forceful, resounding blow. Often implies a lack of precision or a sudden, vigorous movement.
He had to whack the old television to make the picture clear.
The gardener had to whack the tall weeds with a heavy stick to clear a path.
After the engine stalled for the third time, the frustrated mechanic decided to whack the starter motor with a mallet, hoping a physical shock would reset the internal components.
Uncertain. Originally Scottish; probably onomatopoeic, but compare Middle English thakken, from Old English þaccian (whence Modern thwack by conflation with whack). Sense 6 of the verb is likely a semantic loan from Malay hentam (“to strike; to do something carelessly”).
The verb is transitive and requires a direct object. In informal British English, it can also mean to put or place something somewhere quickly.