Definition of "thwack" in English

verb

To hit (someone or something) hard, especially with a flat implement or a stick; to thrash, to whack.
To drive or force (someone or something) by, or as if by, beating or hitting; to knock.
To pack (people or things) closely together; to cram.
To decisively defeat (someone) in a contest; to beat, to thrash.
To crowd or pack (a place or thing) with people, objects, etc.
To fall down hard with a thump.
To be crammed or filled full.
Of people: to crowd or pack a place.

noun

An act of hitting hard, especially with a flat implement or a stick; a whack; also, a powerful stroke involved in such hitting; a blow, a strike.
A dull or heavy slapping sound.

interjection

Used to represent the dull or heavy sound of someone or something being hit or slapped.