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English definition of “knock”

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knock

verb uk   /nɒk/ us    /nɑːk/

knock verb (MAKE NOISE)

B1 [I] to repeatedly hit something, producing a noise: She knocked on the window to attract his attention. There's someone knocking on/at the door. Please knock before entering. [I] specialized engineering If an engine is knocking, it is producing a repeated high sound either because the fuel is not burning correctly or because a small part is damaged and is therefore allowing another part to move in ways that it should not. [I] If something such as a pipe knocks, it makes a repeated high sound.
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knock verb (HIT)

B1 [I + adv/prep, T] to hit, especially forcefully, and cause to move or fall: He accidentally knocked the vase off the table. She knocked her head against the wall as she fell. Who knocked over that mug of coffee? [+ obj + adj ] Some thug knocked him unconscious/senseless. She took a hammer and knocked a hole in the wall.knock into each other/knock through If you knock two rooms into each other or knock two rooms through, you remove the wall between them so that they form one room.
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knock verb (CRITICIZE)

[T] UK informal to criticize, especially unfairly: Don't knock him - he's doing his best.

knock

noun [C] uk   /nɒk/ us    /nɑːk/

knock noun [C] (NOISE)

a sudden short noise made when someone or something hits a surface: There was a knock at/on the door.

knock noun [C] (HIT)

the act of something hard hitting a person or thing: He received a nasty knock on the head from a falling slate.
(Definition of knock from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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