knocks; knocked; knocking
1
: to hit something (such as a door) with the knuckles of your hand or with a hard object (such as a knocker) in order to get people's attention
I heard someone knocking (at the door).
—usually + onI knocked on the door but no one answered.
He knocked on the table to call the meeting to order.
Campaign workers have been knocking on doors throughout the neighborhood. [=have been going to each house or apartment in the neighborhood to talk with the people who live there]
—sometimes used figurativelya talented young singer who is knocking on the door of success [=who is very close to achieving success]
2
always followed by an adverb, adjective, or preposition
: to hit (something or someone) in a forceful way
The ball knocked him on the chin.
knock one stick against another = knock two sticks together
She knocked the glass from his hand.
He knocked the baseball over the fence.
The ball hit him in the mouth and knocked out one of his teeth.
The wind knocked him backwards.
The wind almost knocked him off his feet. = The wind almost knocked him to the ground. [=the wind hit him so hard that he almost fell to the ground]
The collision knocked him unconscious/senseless. [=caused him to become unconscious]
The collision knocked him flying. [=sent him flying through the air]
3
always followed by an adverb or preposition
: to touch or hit someone or something in a way that is not planned or intended
The dog knocked against the lamp.
My knee accidentally knocked against the table.
Skaters were knocking into each other all over the ice.
I kept knocking against him during the bumpy ride. = He and I kept knocking together during the bumpy ride.
I accidentally knocked my knee against the table.
4
: to make (something, such as a hole) by hitting something
He used a hammer to knock a hole in the wall.
5
informal
: to criticize (someone or something)
He's always knocking the government.
Don't knock it until you've tried it. [=wait until you try something before criticizing it]
6
: to produce a repeated loud noise
The engine was knocking.
The pipes were knocking.
plural knocks
1
a
: a hard, sharp hit
He gave him a knock on the head.
b
: the sound made by a hard hit
There was a loud knock at the door.
2
informal
: an experience that makes you less confident or successful for a period of time : a difficult or painful experience
She took some knocks early in her career.
Most performers have their share of knocks [=setbacks] on their way to stardom.
3
informal
: a critical or negative comment
He likes praise but can't stand the knocks.
—often used in U.S. English in the phrase the knock againstThe knock against her is that she can't win the important matches. [=people say that she cannot win the important matches]
One of the knocks against television is that there are too many commercials.
4
: a loud noise produced by an engine when it is not working properly
We heard a knock in the engine.
a type of fuel that reduces engine knock
Cite this Entry
“Knock.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/knock. Accessed 15 Apr. 2026.
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