English Reference
verb · noun

flex

v. · n.
US /ˈfɫɛks/ UK /flˈɛks/ flex UK spelling flexes

  1. 01 B2 Upper Intermediate

    v.to tighten your muscles to show how strong you are.

    v.to contract or tighten a muscle, typically to demonstrate strength or prepare for physical exertion.

    Simple

    The bodybuilder began to flex his arms as soon as he stepped onto the stage.

    In context

    Before the heavy lifting began, the athlete paused to flex his quadriceps, ensuring the muscles were warm and responsive.

  2. 02 B2 Upper Intermediate

    v.to bend something that is flexible.

    v.to bend a functional part or a flexible material without breaking it.

    Simple

    You can flex the plastic ruler quite a bit before it snaps.

    In context

    Modern aircraft wings are designed to flex significantly during turbulence to absorb structural stress.

    stiffenstraighten
  3. 03 B2 Upper Intermediate SlangInformal

    v.to show off your money, success, or expensive things to impress people.

    v.to boast or flaunt one's wealth, status, or achievements in an ostentatious manner.

    Simple

    He bought a luxury watch just to flex on his old classmates.

    In context

    Social media influencers often use their platforms to flex their lifestyle, posting photos of private jets and designer clothing to maintain their brand image.

  4. 04 B2 Upper Intermediate SlangInformal

    n.an act of showing off or something that is impressive.

    n.an instance of boasting or an ostentatious display intended to impress others.

    Simple

    Posting your high test scores on the group chat was a bit of a flex.

    In context

    Mentioning his connection to the CEO during the first five minutes of the interview was a subtle but clear flex.

    Usage

    Often used in the phrase 'weird flex but okay' to describe a strange boast.

  5. 05 C1 Advanced British English

    n.a flexible electrical wire or cord used for a tool or lamp.

    n.a flexible, insulated electrical cable, typically connecting an appliance to a mains plug.

    Simple

    The iron has a long flex so you can reach across the whole board.

    In context

    The safety inspector noted that the flex on the industrial vacuum was frayed and required immediate replacement.

I get to make this show, play the roles and flex the muscles that I never get to flex.

The Guardian· 20 Aug 2026

From Latin flexus, past participle of flecto (“to bend”).

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

This entry
Origin Latin flexus
Level B2 · Upper Intermediate
Frequency Frequent
Updated