English Reference
noun · adjective

knockout

n. · adj.
US /ˈnɑˌkaʊt/ UK /nˈɒkaʊt/ knock·out UK spelling knockouts

  1. 01 B1 Intermediate Sport

    n.a hit that makes a fighter unconscious or unable to continue the fight.

    n.the act of rendering an opponent unconscious or unable to resume a contest within a specified time limit.

    Simple

    The champion won the match with a powerful knockout in the third round.

    In context

    The referee stopped the bout immediately after the knockout, ensuring the medical team could attend to the fallen fighter without delay.

  2. 02 B2 Upper Intermediate Sport

    n.a competition where a player or team is removed after losing one game.

    n.a tournament format in which the loser of each match is immediately eliminated from the competition.

    Simple

    Our local team was eliminated in the first round of the knockout.

    In context

    The knockout stages of the tournament often produce more dramatic results because there is no margin for error in a single-elimination format.

    round robin
  3. 03 B2 Upper Intermediate Informal

    n.someone who is extremely attractive or beautiful.

    n.an exceptionally attractive or impressive person, often used to describe a woman.

    Simple

    Everyone turned to look when she walked in; she was a total knockout.

    In context

    The lead actress was a complete knockout, though critics argued that her performance lacked the depth required for such a complex role.

  4. 04 C2 Proficiency Technical Science

    n.the process of turning off a specific gene in a living thing for science.

    n.the genetic engineering technique of deactivating a specific gene to observe the resulting phenotypic changes.

    Simple

    The scientists used a gene knockout to study how the heart develops.

    In context

    By creating a knockout mouse, the researchers were able to demonstrate that the specific protein was essential for long-term memory formation.

    deactivationinactivation
  5. 05 B2 Upper Intermediate Informal

    adj.extremely impressive, beautiful, or successful.

    adj.strikingly attractive or impressive; having a powerful effect.

    Simple

    She wore a knockout dress to the awards ceremony.

    In context

    The marketing team delivered a knockout presentation that secured the contract despite stiff competition from larger agencies.

After a headline-snatching first senior century on Tuesday , the 18-year-old's One-Day Cup drew to a close with 22 in Lancashire's defeat by Durham in the knockout stage on Friday.

BBC News· 15 Aug 2026

Chelsea’s vice-captain popped up with crucial late goals for Argentina in the knockout stages, including a winning header against Egypt and the equaliser against England.

The Guardian· 12 Aug 2026

Deverbal from knock out.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Level B2 · Upper Intermediate
Frequency Frequent
Updated