knock
knock — noun
1. a short, sharp sound produced when a hand or object hits a hard surface, especia
a short, sharp sound produced when a hand or object hits a hard surface, especially a door or window, often to get someone's attention
Élise heard a knock at the door and went to answer it.
knock at the door — common pattern for entry
There was a loud knock on the classroom window, and everyone turned to look.
A soft knock came from the bedroom, but nobody was inside.
soft knock — adjective + knock for volume
The postman gave three quick knocks before leaving a package by the door.
- loud knock
- soft knock
- quick knock
- knock at the door
- knock on the window
Grammar Patterns
a knock + at/on + [door/window]
Usage Note
Countable noun, usually singular when referring to a single incident. Often preceded by a possessive form of the person who hears it (e.g., 'I heard a knock'; 'She was woken by a knock').
Common Mistakes
2. a hard hit from an object or person that lands on a body part or surface, often
a hard hit from an object or person that lands on a body part or surface, often causing pain or damage
The knock on his knee left a purple bruise that lasted for a week.
knock on + body part for impact location
Beatriz took a hard knock to the shoulder when she slipped on the wet floor.
take a knock — collocation for receiving a hit
The wooden table had several knocks and scratches from years of use.
Vivek got a nasty knock on the head when the ladder fell sideways.
- hard knock
- nasty knock
- take a knock
- get a knock
- knock to the head
Grammar Patterns
a knock + to/on + [body part]
Usage Note
Countable noun. Often used with 'take a knock' (receive a blow) or 'get a knock' (suffer a blow). Not used for deliberate violent attacks such as punches in a fight — 'punch' or 'blow' would be more natural there.
Common Mistakes
3. unkind or unfair critical remarks about a person, idea, or thing
unkind or unfair critical remarks about a person, idea, or thing
The biggest knock against the new café is that the coffee is too expensive.
the biggest knock against — common critical framing
Sivan accepted the knocks from the audience and used them to improve her presentation.
One common knock on the proposal is that it does not address safety concerns.
common knock on — frequent phrase for repeated criticism
The mayor has taken plenty of knocks from the press over the new policy.
- biggest knock
- main knock
- common knock
- knock against
- knock on
- take knocks
- praise
expression of approval, the opposite of criticism
Grammar Patterns
a/the knock + against + [person/thing]
Usage Note
Countable noun, found mostly in informal contexts such as journalism, reviews, and everyday conversation. Often appears in the structure 'the knock against [something] is [criticism]'.
Common Mistakes
4. a negative event that damages someone's confidence, hopes, plans, or wellbeing
a negative event that damages someone's confidence, hopes, plans, or wellbeing
Losing her job was a serious knock to Valentina's confidence.
knock to confidence — metaphor for emotional setback
The team's early defeat was a huge knock to their championship hopes.
Small businesses suffered a severe knock when the local factory closed down.
suffer a knock — verb collocation for receiving setback
Failing the exam was a knock, but Wren studied harder and passed the next time.
- serious knock
- huge knock
- severe knock
- knock to confidence
- knock to hopes
- suffer a knock
- boost
something that lifts confidence or spirits
Grammar Patterns
a knock + to + [emotion/confidence/plans]
Usage Note
Countable noun, almost always singular. The pattern 'a knock to [abstract noun]' is very common. Stronger than 'disappointment' — implies actual damage or loss rather than simply feeling let down.
Common Mistakes
knock — verb
1. to strike a hard surface such as a door or window with your hand or an object, e
to strike a hard surface such as a door or window with your hand or an object, especially to get someone's attention or announce your presence
Élise knocked on the office door before stepping inside.
knock on + door — most common intransitive pattern
A delivery driver was knocking loudly at the front gate, but nobody heard.
Takeshi knocked three times and then pushed the door open slowly.
knock + number of times — quantity pattern
The teacher knocked her pen against the desk to get the class's attention.
knock + object + against + surface — transitive pattern
- knock on the door
- knock at the window
- knock loudly
- knock gently
- knock twice
Grammar Patterns
knock + on/at + [door/window]
knock + [object] + on + [surface]
Usage Note
When used intransitively, the preposition is 'on' (American and British) or 'at' (more common in British English for doors). When transitive, the object is the thing you strike the surface with, not the surface itself (e.g., 'knock your fist on the table', not 'knock the table').
Common Mistakes
2. If an engine knocks, it produces a repeated metallic tapping sound caused by imp
If an engine knocks, it produces a repeated metallic tapping sound caused by improper fuel burning or a faulty component.
The old truck's engine started knocking after Mert filled it with cheap fuel.
engine started knocking — common verb + start pattern
Valentina heard the engine knocking on the highway and pulled over immediately.
A knocking engine often means the spark plugs need to be replaced soon.
knocking engine — attributive adjective use
If your engine knocks, take it to a mechanic before the damage gets worse.
- engine knocks
- start knocking
- knocking sound
- knocking noise
- car engine knocks
Grammar Patterns
[engine] + knocks
[engine] + is knocking
Usage Note
Intransitive only — the subject is always the engine or vehicle. The technical term for this condition is 'engine detonation' or 'engine pinging'. Not used metaphorically (you cannot say 'my stomach is knocking' to mean growling).
Common Mistakes
3. to make repeated tapping or banging sounds inside a building's pipes, radiator,
to make repeated tapping or banging sounds inside a building's pipes, radiator, or heating system, often due to temperature changes, trapped air, or water pressure
The pipes in the bathroom knock every time someone turns on the hot water.
pipes knock — subject + intransitive verb pattern
Sofie called the plumber because the radiator was knocking all night.
The heating system knocks loudly when it first turns on in the morning.
Old houses often have knocking pipes that need to be fixed by a professional.
knocking pipes — attributive adjective use
- pipes knock
- radiator knocks
- knocking pipes
- knocking radiator
- heating system knocks
Grammar Patterns
[pipe/radiator/heating] + knocks
Usage Note
Intransitive only. The typical problem is called 'water hammer' in plumbing. Distinguished from verb sense 2 (engine noise) by the subject: pipes/radiators vs. engines. Common in home-maintenance discussions.
Common Mistakes
4. to strike someone or something with enough force to make them move, fall, leave
to strike someone or something with enough force to make them move, fall, leave a position, or enter a different state
Christopher accidentally knocked the glass off the table with his elbow.
knock + object + off + surface — direction pattern
The strong wind knocked several flower pots off the balcony railing.
Femi knocked the ball across the field during the final minute of the game.
A cyclist came around the corner and nearly knocked the old woman over.
knock + person + over — common phrasal pattern
The toddler knocked a whole stack of picture books off the library shelf.
- knock over
- knock off
- knock down
- knock into
- knock across
- knock against
- accidentally knock
Grammar Patterns
knock + [object] + [adverb/preposition]
knock + [object] + off/over/down/into + [target]
Usage Note
Transitive verb with an object (the person/thing hit) and typically a directional adverb or prepositional phrase (off, over, down, into, across). The direction component is almost always required — 'I knocked the cup' is incomplete; 'I knocked the cup off the table' is correct.
Common Mistakes
5. to remove a wall that separates two rooms, usually to create one larger living s
to remove a wall that separates two rooms, usually to create one larger living space
The Watanabes decided to knock the wall between the kitchen and the dining room.
knock + the wall between [room] and [room]
The Watanabes paid a builder to knock through from the living room into the study.
If you knock down the dividing wall, the ground floor will feel much more spacious.
The couple knocked two small bedrooms into one large master bedroom.
- knock through
- knock down a wall
- knock a wall between
- knock into one room
- build
to construct a wall, the opposite of removing one
Grammar Patterns
knock + [wall] + down/through
knock through + [prepositional phrase]
Usage Note
Often used as a phrasal verb 'knock through' (remove part of a wall to connect rooms) or 'knock down' (completely demolish a wall). Not used for removing external walls (that is 'demolish').
Common Mistakes
6. to say unkind or unfair things about someone or something, often in a repeated o
to say unkind or unfair things about someone or something, often in a repeated or habitual way
Critics knocked the film for its weak storyline, but audiences loved it anyway.
knock + [something] + for + [reason] — criticism pattern
Mert's colleagues are always knocking his ideas without offering better ones.
Diya knocked the city's bike lane plan at the town hall meeting, but the mayor defended it.
Stop knocking yourself all the time — you did an excellent job on the project.
knock yourself — reflexive use for self-criticism
- knock someone/something
- always knocking
- keep knocking
- knock yourself
- knock an idea
- praise
to express warm approval or admiration
- compliment
to politely express praise
Grammar Patterns
knock + [person/thing]
always + knocking + [person/thing]
Usage Note
Informal verb, more common in spoken English and journalism than in formal writing. Often conveys that the criticism is unfair or excessive. The reflexive form 'knock yourself' (criticize yourself) is very common in spoken encouragement.
Common Mistakes
knock over
phrasal verbto hit someone or something so that they fall from an upright position to the ground or a flat surface
Putri accidentally knocked over a cup of hot coffee while reaching for her phone.
A careless shopper knocked over a display of canned goods at the supermarket.
knock down
phrasal verbto cause someone or something to fall to the ground by hitting them with force, or to demolish a building or wall completely
The wind was so strong that it knocked down the garden fence.
The city plans to knock down the old hospital and build apartments in its place.
knock out
phrasal verbto hit someone so hard that they become unconscious; or to defeat and remove a person or team from a competition
The boxer knocked out his opponent in the second round with a powerful right hook.
Brazil was knocked out of the World Cup in the quarter-finals by a surprise goal.
knock off
phrasal verbto stop working for the day; or to reduce the price of an item by a certain amount; or (slang) to steal something
The construction workers knocked off at five o'clock and headed to the pub.
The seller agreed to knock twenty dollars off the original price of the sofa.
knock up
phrasal verbespecially British: to wake someone by knocking on their door
Could you knock me up at six o'clock tomorrow morning? I have an early flight.
The hotel receptionist agreed to knock up the sleeping guest when the taxi arrived.
knock through
phrasal verbto remove part of a wall between two rooms in order to make them into one larger room
The owners decided to knock through the wall connecting the kitchen and dining area.
After knocking through, the small flat felt twice as big.
knock around
phrasal verbTo travel or spend time in a casual way without a fixed plan.
We spent the summer knocking around Europe.
He likes to knock around with his friends on weekends.
knock around together
phrasal verbTo spend time together as friends in a casual way.
The two brothers used to knock around together a lot.
We've been knocking around together since college.
knock around with
phrasal verbTo spend time with someone as a friend or companion.
She knocks around with a group of artists.
I used to knock around with him in high school.
knock back
phrasal verbTo drink something quickly, especially alcohol.
He knocked back a glass of water after the run.
She knocked back two beers in ten minutes.
knock together
phrasal verbTo make or assemble something quickly and roughly.
He knocked together a bookshelf from old boards.
We knocked together a quick meal before the movie.
knock on wood
idioma phrase said after mentioning something good about your situation, to express the wish that your good luck will continue without being spoiled by bad luck
I have never broken a bone in my life, knock on wood.
The project is going well so far, knock on wood, but we still have a lot of work ahead.
knock it off
idiomused to tell someone angrily or firmly to stop doing something that is annoying or unpleasant
Knock it off, you two! I can not concentrate with all that shouting.
The boy kept tapping his pencil on the desk until the teacher told him to knock it off.
take a knock
idiomto be damaged or badly affected by a difficult experience or event
Her confidence took a knock after she failed the driving test for the third time.
The local economy took a serious knock when the factory closed down last year.
To force people to stop arguing and start acting reasonably.
The manager banged their heads together to end the pointless fight.
If you two don't stop, I'll knock your heads together.
To hit someone very hard many times, causing serious injury.
The bully threatened to beat the daylights out of Tom.
If you touch my bike, I'll knock the living daylights out of you.
To hit someone or something very hard and repeatedly.
The storm kicked hell out of the old barn.
He threatened to knock hell out of anyone who disagreed.
To greatly surprise or impress someone.
Her performance at the concert blew everyone's socks off.
The new design will knock your socks off.
To train or improve someone so they perform a job or task well.
The coach knocked the new players into shape within weeks.
We need to get the intern into shape before the project starts.
To make something more acceptable, organized, or successful.
She knocked the messy report into shape before the meeting.
It took months to get the business back into shape.
To affect someone very deeply, often causing shock or upset.
The news of her father's illness knocked her for six.
Losing the championship hit the team for six.
Used as a threat to say you will hit someone.
If you don't leave now, I'll knock your block off!
He shouted, 'I'll knock your head off if you touch that!'
knock somebody dead
idiomTo impress someone very much, especially with your appearance or performance.
You look amazing in that dress—you'll knock them dead.
Her speech knocked the audience dead.
To be much better than someone or something.
Her cooking knocks mine into a cocked hat.
This new software knocks the old version into a cocked hat.
knock it off!
idiomUsed to tell someone to stop making noise or annoying you.
Knock it off, you two—I'm trying to study.
The teacher told the class to knock it off.
To cause someone to lose their position of success or admiration.
The scandal knocked the politician off his pedestal.
The new champion knocked the old one off his perch.
To stop something from happening or to stop doing something.
The bad weather knocked our picnic plans on the head.
We were tired, so we knocked the game on the head early.
To surprise or shock someone so much they cannot react immediately.
The sudden job loss knocked her sideways.
His unexpected proposal knocked me sideways.
To try to persuade someone to stop behaving foolishly, sometimes using force.
His father tried to knock some sense into him about his spending.
Can you talk some sense into your brother before he quits school?
To be much better than someone or something.
Her essay knocks spots off all the others.
This restaurant knocks spots off the one we went to last week.
To make someone lose their confidence and enthusiasm.
Failing the exam knocked the stuffing out of him.
The harsh criticism knocked the stuffing out of the young writer.
Used to express great surprise.
When she said she was moving to Japan, you could have knocked me down with a feather.
You could have knocked me down with a feather when I won the lottery.
Word family
Synonym discussion
Sense: verb/4
These four verbs share the core meaning of coming into contact with force, but differ in intention and result. 'Hit' is the most general word — it covers everything from accidentally touching a table to deliberately punching someone ('The ball hit the window'). 'Strike' is more formal and often implies a deliberate, forceful action ('The ship struck a rock'). 'Bump' is lighter and almost always accidental, involving slower movement ('The car bumped into the gate'). 'Bang' is louder and more violent, often suggesting a sharp, noisy impact ('She banged the door shut'). Use 'knock' (verb/4) when the contact causes something to move, fall, or change position — which 'hit' and 'strike' do not necessarily imply. For example: 'I hit the cup' (contact only) vs. 'I knocked the cup off the table' (contact + movement). 'Bump' can also cause movement but with less force, while 'bang' adds a noise element that 'knock' does not require.
Common collocations
Etymology
The word 'knock' comes from Old English 'cnocian', meaning to strike or beat, which itself was probably formed in imitation of the sound of knocking (onomatopoeia). Similar words exist in other Germanic languages, such as Old Norse 'knoka' (to beat) and Middle Dutch 'cnoken' (to knock). The first recorded use dates back to around the year 1000. By the late 19th century, 'knock' had developed the informal sense 'to criticize', possibly from the idea of striking with words. The automotive meaning (engine knocking) appeared in the early 20th century with the rise of the internal combustion engine.