"whack" in the noun sense
1. whack
the sound made by a sharp swift blow
2. knock, belt, rap, whack, whang
the act of hitting vigorously
"he gave the table a whack"
"whack" in the verb sense
1. whack, wham, whop, wallop
hit hard
"The teacher whacked the boy"
Source: WordNet® (An amazing lexical database of English)
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