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knock (nŏk)
v. knocked, knock·ing, knocks
1. To strike with a hard blow: knocked him on the head.
2. To affect in a specified way by striking hard: knocked the mugger senseless.
3. To cause to be displaced or unengaged; force: a wind that knocked the tower over; a blunder that knocked him out of the job.
4. To cause to collide: I knocked my head on a low beam.
5. To produce by hitting or striking: knocked a hole in the wall.
6. Informal To find fault with; criticize: Don't knock the food; it's free.
1. To strike a sharp audible blow or series of blows, as on a door.
2. To collide with something: knocked into the table.
3. To make a pounding or clanking noise: The car engine is knocking.
1. An instance of striking or colliding.
2. The sound of a sharp blow on a hard surface.
3. A pounding or clanking noise made by an engine, often as a result of faulty fuel combustion. Also called ping.
4. Slang A cutting, often petty criticism.
Phrasal Verbs:
knock around (or about) Informal
1. To be rough or brutal with; maltreat.
2. To wander from place to place: knocking around Europe.
3. To discuss or consider: met to knock around some ideas.
knock back Informal
To gulp (an alcoholic drink).
knock down
1. To bring to the ground with a blow or other forceful action; topple.
2. To disassemble into parts, as for storage or shipping.
3. To declare sold at an auction, as by striking a blow with a gavel.
4. To reduce in amount or intensity: a retailer who knocked down the price by 20 percent; firefighters who knocked down the fire enough to search the house.
5. Slang To receive as wages; earn: knocks down $50 an hour.
knock off
1. Informal
a. To take a break or rest from; stop: knocked off work at noon.
b. To cease work: It's after five; let's knock off.
2. Informal To complete, accomplish, or dispose of hastily or easily; finish: That author knocks off a book a year.
3. Informal To get rid of; eliminate: knocked off 12 pounds in a month.
4. Slang To kill or overcome.
5. Slang To hold up or rob: knocked off a bank.
6. Informal To copy or imitate, especially without permission: knocking off someone else's ideas.
knock out
1. To render unconscious.
2. Sports To defeat (a boxing opponent) by a knockout.
3. To render useless or inoperative: The storm knocked out the phones.
4. Informal To excite or overwhelm, especially by being sexually attractive.
5. Informal To exert or exhaust (oneself or another) to the utmost: knocked herself out to be ready on time.
6. Informal To produce in abundance: The workers knocked out 500 parts in one hour.
7. To inactivate (a gene or genes) by genetic manipulation so that the resulting phenotypic effects can be observed.
knock together
To make or assemble quickly or carelessly.
knock up
1. Derogatory Slang To make pregnant.
2. Chiefly British To wake up or summon, as by knocking at the door.
3. Chiefly British To wear out; exhaust.
have it knocked Slang
To be certain of success: "He knew he had it knocked after he saw a rough cut of Chinatown" (Time).
knock cold
To render unconscious; knock out.
knock dead
1. To kill with a blow.
2. Slang To affect strongly and positively: a performance that knocked the audience dead.
knock it off Slang
To stop doing something. Often used in the imperative: He asked us to knock it off.
knock out of the box Baseball
To force the removal of (an opposing pitcher) by heavy hitting.
knock (someone's) socks off Slang
To overwhelm or amaze.
knock some sense into Slang
To beat or hit (someone) in an effort to teach a lesson or cause a person to adopt an acceptable pattern of behavior.

[Middle English knokken, from Old English cnocian.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Indo-European & Semitic Roots Appendices

    Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

    Indo-European Roots

    Semitic Roots

    The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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