flex

¹ American  

[fleks] / flɛks /

verb (used with object)

1. to bend, as a part of the body.

   He flexed his arms to show off his muscles.

2. to tighten (a muscle) by contraction.

3. to demonstrate (one’s ability, expertise, etc.).

   She’s flexed her marketing skills for various clients in the publishing industry.

4. Slang. to boast or brag about; flaunt.

   He’s just not into flexing his success.

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verb (used without object)

1. to bend.

2. Slang. to boast or brag; show off.

   In his rap lyrics he flexes about his fancy lifestyle.

noun

1. the act of flexing.

2. Slang. a boast or brag.

   It's not a flex, but we have the best burgers here.

3. British.

   1. any flexible, insulated electric cord; an electric cord or extension cord.

   2. Slang. an elastic band, as a garter.

4. Mathematics. an inflection point.

verb phrase

1. flex on to brag or show off to; assert one’s dominance or superiority over.

   She’s flexing on her haters by posting new photos of her beautiful family.

flex ² American  

[fleks] / flɛks /

adjective

1. Informal. flexible.

   a flex program of workers' benefits.

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flex- ³ American  

Also flexi-.

1. a combining form representing flexible in compound words.

   flextime.

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flex British  

/ flɛks /

noun

1. US and Canadian name: cord.  a flexible insulated electric cable, used esp to connect appliances to mains

2. informal flexibility or pliability

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verb

1. to bend or be bent

   he flexed his arm

   his arm flexed

2. to contract (a muscle) or (of a muscle) to contract

3. (intr) to work according to flexitime

4. to test or display (one's authority or strength)

Usage

What else does flex mean? Flex is a slang term meaning "to show off," whether it be your physique, your belongings, or some other thing you consider superior to those of others. The act of flexing is often criticized as a power move, considered arrogant and insincere.

Etymology

Origin of flex¹

First recorded in 1515–25; (adjective) from Latin flexus, past participle of flectere “to bend, turn”; (noun) from Latin flexus act of bending, equivalent to flect(ere) + -tus suffix of verbal action

Origin of flex²

Shortening of flexible

Explanation

When you flex something, you bend or contract it. To appear super tough, you might flex your archery bow while flexing your muscles. Things curve and bend when they flex, whether they're human joints or objects made of a bendable material like plastic or soft wood. Another way to flex is to tense or contract a muscle: "The weightlifter flexes her biceps." Experts suspect that flexible came first, from the Latin root flexibilis, "flexible, pliant, or yielding," and figuratively, "tractable, or easily influenced."

Example Sentences

You can tell the Pentagon loves it because it just airlifted a microreactor to Utah on a C-17 — the military equivalent of posting a flex on Instagram.

From MarketWatch • Mar. 26, 2026

But here’s the quiet flex: toast them first.

From Salon • Mar. 11, 2026

There is flex capacity for coal available in South Asia, which has opened new plants for the commodity recently, they say.

From The Wall Street Journal • Mar. 5, 2026

It's like a wing with a flexible, corrugated structure within it – something like an accordion – that allows said wing to fold down quickly, or flex with ease.

From BBC • Mar. 3, 2026

I point and flex my foot, stretching and tensing through my entire leg as much as I can.

From "The Sea in Winter" by Christine Day

Related Words

• lean
• tighten
• tilt