flex

verb

ˈfleks 

flexed; flexing; flexes

transitive verb

1

: to bend especially repeatedly

2

a

: to move muscles so as to cause flexion of (a joint)

b

: to move or tense (a muscle) by contraction

3

: use, demonstrate

flexing her skills as a singer

intransitive verb

1

: bend

2

informal

a

: to talk in a boastful or aggressive way

"Bronze" is one of the most straightforward new tracks: a boastful and insidiously dark song that sees him flexing about his many wins.

—Raisa Bruner

—often used with on to indicate the person, group, etc. at whom the talk is directed

Hip-hop has never just been about selling drugs, flexing on haters, and threatening enemies, as many like to portray it.

—Aaron Williams

… he … went searching for criticism, then tried to flex on a random criticizer.

—Ashley Feinberg

"… And if President Trump is going to continue to flex on China, whether it's with tariffs, whether it's just talking tough and tweeting tough, that still draws a very stark contrast between himself and the Democratic Party. …"

—Mattie Duppler

b

: to make an ostentatious display of something : show off

While tons of influencers love to flex on Instagram via designer bags and other luxury splurges, others are all about that perfect high-low balance …

—Bella Gerard

—often used with on to indicate the person, group, etc. at whom the display is directed

It's in-your-face branding that is all about flexing on your friends in their more common, more conventional limousines.

—Max Finkel

see also:

flex one's muscles

Examples of flex in a Sentence

He flexed the muscles of his right arm.

a material that flexes easily

Recent Examples on the Web

Mark Ronson flexed the elegantly minimal Audemars Piguet Royal Oak designed in collaboration with Matthew Williams of Alyx fame. —Rachel Cormack, Robb Report, 6 June 2026

Towns flexing on Wembanyama was the icing on the cake. —Fiifi Frimpong, New York Daily News, 6 June 2026

Mostly, the post demonstrated how the president, who has flexed his political muscles in recent primary races and remains the most dominant force in the Republican Party, is not taking kindly to growing congressional unease with the conflict. —Zachary Schermele, USA Today, 5 June 2026

Ellis was more assertive about flexing the little agency’s full compliance arsenal. —Megan Molteni, STAT, 5 June 2026

Word History

Etymology

borrowed from Latin flexus, past participle of flectere "to cause to go in a different direction, bend, curve," of uncertain origin

First Known Use

circa 1521, in the meaning defined at transitive sense 1

Phrases Containing flex

• flex-cuff
• flex-fuel
• flex one's muscles

Rhymes for flex

• becks
• checks
• czechs
• decks
• dex
• ex
• flecks
• hex
• lex
• necks
• pecks
• plex

Kids Definition

flex

verb

ˈfleks

1

: to bend especially over and over

2

a

: to move muscles so as to cause flexion of

b

: to move or tense (a muscle) by contraction

Medical Definition

flex

transitive verb

ˈfleks 

1

: to bend especially repeatedly

2

a

: to move muscles so as to cause flexion of (a joint)

stretching and flexing his knees

b

: to move or tense (a muscle or muscles) by contraction

flexed their biceps