triangle

noun tri·an·gle \ ˈtrī-ˌaŋ-gəl \

|Updated on: 17 Jul 2018

Definition of triangle

1 : a polygon having three sides — compare spherical triangle

2 a : a percussion instrument consisting of a rod of steel bent into the form of a triangle open at one angle and sounded by striking with a small metal rod

b : a drafting instrument consisting of a thin flat right-angled triangle of wood or plastic with acute angles of 45 degrees or of 30 degrees and 60 degrees

3 : a situation in which one member of a couple is involved in a love affair with a third person

See triangle defined for English-language learners

See triangle defined for kids

Examples of triangle in a Sentence

She cut the sandwiches into triangles.

Recent Examples of triangle from the Web

Decked out in furs, jewels and flawless blonde curls, Sugarland songstress Jennifer Nettles stars in the video as a wealthy 1960s housewife caught in a torrid love triangle opposite Brandon Routh and Taylor Swift.

— shanté honeycutt, Billboard, "Sugarland & Taylor Swift's Glamorous 'Babe' Video Depicts a Retro Love Triangle," 9 June 2018
He's locked in a love triangle with his friend William (Kaalan Walker) and a troubled girl, Nicole (Rachel Hilson), and the trio's experience is moody and tragic, a dark, violent journey that's near-Lynchian in its style and tone.

— katie walsh, latimes.com, "'Kings' confounds with a take on the L.A. riots starring Halle Berry that’s largely naive," 26 Apr. 2018
Sliced carrots, yellow peppers and cauliflower arranged in a triangle will do the trick.

— mali anderson, Milwaukee Journal Sentinel, "Ideas for celebrating Halloween with kids: From the not-so-scary to the downright spooky," 16 Oct. 2017
Princess Tsianina’s own story, in fact, was the inspiration for the opera, in which the heroine, disillusioned by urban life and caught in a romantic triangle, returns to the values of her tribal society.

— mark swed, latimes.com, "Before ‘Hamilton,’ 100 years of American music theater and how it’s told the story of who we are," 29 June 2018
That same triangle, a symbol of death, became recast as ACT-UP’s defining symbol for gay liberation.

— sonia k. katyal, BostonGlobe.com, "The sudden rush of vulgar trademarks," 23 June 2018
The men are shapes, such as triangles, and the women are straight lines, like needles.

— john j. miller, WSJ, "A Multidimensional Religious Story," 8 June 2018
The only engine to truly break the mold—the only one to make it into production—was engineer Felix Wankel’s rotary wonder, a triangle inside an oval, spinning like a demon.

— blake z. rong, Popular Mechanics, "The Evolution of the Combustion Engine," 5 June 2018
Images of eagles, triangles, globes and the number 32 repeat throughout the hall.

— sean erwin, miamiherald, "Orchestra Miami's 'The Magic Flute' is Mozart's answer to 'Hamilton' | Miami Herald," 7 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'triangle.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Illustration of triangle

Origin and Etymology of triangle

Middle English, from Anglo-French, from Latin triangulum, from neuter of triangulus triangular, from tri- + angulus angle

NEW! Time Traveler

First Known Use: 14th century

in the meaning defined at sense 1

See Words from the same year

TRIANGLE Defined for English Language Learners

triangle

noun

Definition of triangle for English Language Learners

: a shape that is made up of three lines and three angles
: something that is shaped like a triangle
: a musical instrument that is made of a steel rod bent into the shape of a triangle and that you play by hitting with a metal rod

TRIANGLE Defined for Kids

triangle

noun tri·an·gle \ ˈtrī-ˌaŋ-gəl \

Definition of triangle for Students

1 : a flat geometric figure that has three sides and three angles

2 : something that has three sides and three angles

a triangle of land

3 : a musical instrument made of a steel rod bent in the shape of a triangle with one open angle

Medical Dictionary

triangle

noun tri·an·gle \ ˈtrī-ˌaŋ-gəl \

medical Definition of triangle

: a three-sided region or space and especially an anatomical one — see anterior triangle, carotid triangle, femoral triangle, posterior triangle, suboccipital triangle