Webster's Revised Unabridged Dictionary · 1913

Whack

Whack , transitive verb

[Compare Thwack.]

1.
To strike; to beat; to give a heavy or resounding blow to; to thrash; to make with whacks. [Colloquial]
Rodsmen were whackingtheir way through willow brakes. — G. W. Cable
2.
To divide into shares; as, to whack the spoils of a robbery; -- often with up. [Slang]

Whack , intransitive verb

To strike anything with a smart blow.
Collocations (1)
To whack away , to continue striking heavy blows; as, to whack away at a log. [Colloquial]

Whack , noun

1.
A smart resounding blow. [Colloquial]
2.
A portion; share; allowance. [Slang]
3.
an attempt; as, to take a whack at it. [Colloquial]
Collocations (1)
Out of whack , out of order. [Slang]