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knock

v. · n.
US //ˈnɑk// UK //nˈɒk// knock
  1. 1 to rap on a surface (v.)
    A2 Elementary

    to hit a surface with your knuckles or a hard object to make a sound, usually to get attention.

    to strike a surface, typically a door, with the knuckles or a knocker to signal one's presence or request entry.

    Example

    I had to knock on the door three times before anyone heard me.

    Example

    The courier had to knock repeatedly on the heavy oak door before the receptionist finally emerged from the back office.

    Usage

    Often used with the preposition 'on'.
  2. 2 to hit or bump (v.)
    B1 Intermediate

    to hit something by accident, often causing it to move or fall.

    to strike or collide with something, often resulting in displacement or damage.

    Example

    Be careful not to knock that vase off the table with your bag.

    Example

    The cyclist was nearly knocked off his bike when a car door opened suddenly in his path.

    Usage

    Frequently used in phrasal verbs like 'knock over' or 'knock down'.
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  1. 3 to criticize (v.)
    B2 Upper Intermediate Informal

    to say negative things about something or someone.

    to criticize or disparage something, often unfairly or habitually.

    Example

    Don't knock it until you've tried it; the food is actually quite good.

    Example

    Critics were quick to knock the director's latest film, though audiences seemed to appreciate its unconventional pacing.
  2. 4 a rapping sound (n.)
    A2 Elementary

    the sound made when someone hits a door or surface.

    the sound produced by a sharp blow or rap against a hard surface.

    Example

    There was a loud knock at the door just as we sat down for dinner.

    Example

    A sharp, rhythmic knock echoed through the hallway, startling the residents who were not expecting visitors so late.
  3. 5 a setback or blow (n.)
    B2 Upper Intermediate Informal

    a difficult experience or a failure that hurts your progress.

    a figurative blow, setback, or unfortunate experience that affects one's confidence or progress.

    Example

    Losing his job was a big knock to his confidence.

    Example

    The company took a serious knock when its main competitor released a cheaper, more efficient version of the same product.
  4. 6 engine noise (n.)
    C2 Proficiency Technical Science

    a metallic sound in a car engine that shows something is wrong.

    a characteristic metallic sound in an internal combustion engine caused by improper combustion.

    Example

    The mechanic said the knock in the engine was caused by low-quality fuel.

    Example

    Persistent engine knock can lead to significant mechanical failure if the timing of the spark ignition is not adjusted immediately.
    • pinging
Origin

From Middle English knokken, from Old English cnocian, ġecnocian, ġecnucian, cnucian (“to knock, pound on, beat”), from Proto-West Germanic knokōn, from Proto-Germanic knukōną (“to knock”), a suffixed form of knu-, knew- (“to pound on, beat”), from Proto-Indo-European gnew-, gen- (“to squeeze, pinch, kink, ball up, concentrate”). The English word is cognate with Middle High German knochen (“to hit”), Old English cnuian, cnuwian (“to pound, knock”), Old Norse knoka (compare Danish knuge (“to squeeze”), Swedish knocka (“to hug”)).

Word family
Idioms19 entries

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