knockdown (Adjective) — (furniture) easily assembled and dismantled. ex. "I bought a knockdown chest at the do-it-yourself store"
knockdown (Adjective) — Strong enough to knock down or overwhelm. ex. "a knock-down blow"
knockdown (Noun) — A blow that knocks the opponent off his feet.
knockdown (Verb) — Cause to come or go down. ex. "The mugger knocked down the old lady after she refused to hand over her wallet"
knockdown (Verb) — Knock down with force. ex. "He knocked down his opponent"
knockdown (Verb) — Shatter as if by explosion.