knockout (Noun) — A very attractive or seductive looking woman.
knockout (Noun) — A blow that renders the opponent unconscious.
knockout (Noun) — An outstanding example of its kind. ex. "his roses were knockouts"
knockout (Noun) — A contest of several rounds in which the loser in each round is eliminated.
knockout (Adjective) — Very strong or vigorous. ex. "a knockout punch"
knockout (Verb) — Eliminate. ex. "knock out a target"
knockout (Verb) — Knock unconscious or senseless. ex. "the boxing champion knocked out his opponent in a few seconds"
knockout (Verb) — Destroy or break forcefully. ex. "The windows were knocked out"
knockout (Verb) — Overwhelm with admiration. ex. "All the guys were knocked out by her charm"
knockout (Verb) — Empty (as of tobacco) by knocking out. ex. "knocked out a pipe"