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Knock - Wikipedia
Knock, to tap on a door Knock, a slang term meaning to render a negative evaluation or assessment Engine knocking, in spark-ignition internal combustion engines Knock Nevis, a Norwegian supertanker formerly known as Seawise Giant, Happy Giant, and Jahre Viking The Knock, another term for hitting the wall, in endurance sports The Knock, a slang term for HM Revenue and Customs, UK tax-collecting ...
To stop doing something. Often used in the imperative: He asked us to knock it off.