tri·an·gle | \ ˈtrī-ˌaŋ-gəl \

Definition of triangle 

1 : a polygon having three sides — compare spherical triangle

2a : 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

Illustration of triangle

Illustration of triangle

triangle 1: 1 equilateral, 2 acute, 3 obtuse, 4 scalene, 5 isosceles, 6 right triangle

Examples of triangle in a Sentence

She cut the sandwiches into triangles.

Recent Examples on the Web

Items on display include three pink-triangle armbands worn by homosexual prisoners incarcerated at the Buchenwald concentration camp, near Weimar, Germany. Lisa J. Huriash,, "Museum documents persecution of gays in Nazi Germany," 10 July 2018 Honey baklava is shaped in logs rather than triangles and filled with tahini, honey, carob syrup, and pistachios. Ann Trieger Kurland,, "She’s on a tahini mission," 9 July 2018 Schnaufer said his experience involved fighting to get folding triangle shaped signs on a sidewalk for the eatery. Lauren Ritchie,, "Lake County Commission candidate Tad Schnaufer pads work, academia background," 3 July 2018 With funding from the Forest Service, REI, Osprey, and PPM, a printing company based in California, the CDTC hopes to put up about 10,000 signs along the trail, most of them 3.5-inch aluminum triangles that will be nailed to posts and trees. Craig Fehrman, Outside Online, "The CDT Gets Blazed," 10 Apr. 2018 But best of all was the opportunity to make their own sounds on the drums, tambourines, clatterpillars, plastic eggs filled with rice, mallets, and triangles. Denise Coffey, Courant Community, "Exploring The Science Of Sound With Sally Rogers," 27 Mar. 2018 Karpeles closes with commentary on bringing the Edge, Lita, Matt Hardy real-life love triangle/angle to WWE TV programming; what makes a successful angle; MLW; The Writers Room podcast; the Florida Panthers; social media; and more. Jim Varsallone, miamiherald, "This Florida Panthers attorney and former WWE writer is now scripting for MLW | Miami Herald," 24 Mar. 2018 Junior Nila Blackford was dominant during the second half and Manual executed a triangle-and-two defense to perfection to rally past Sacred Heart 55-52 in the championship game of the Class Act Seventh Region Tournament at Valley. Jason Frakes, The Courier-Journal, "Manual stuns No. 1 Sacred Heart in Seventh Region girls basketball final," 3 Mar. 2018 Things get even zanier from there, and The Magicians has batty creatures, beautiful new worlds, love triangles and steamy love scenes galore. Kelly Lawler, USA TODAY, "The 10 best sci-fi and fantasy TV shows you’re not watching," 3 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.

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First Known Use of triangle

14th century, in the meaning defined at sense 1

History and Etymology for triangle

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

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Statistics for triangle

Last Updated

25 Sep 2018

Look-up Popularity

Time Traveler for triangle

The first known use of triangle was in the 14th century

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More Definitions for triangle



English Language Learners Definition of triangle

: 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


tri·an·gle | \ ˈtrī-ˌaŋ-gəl \

Kids Definition of triangle

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


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

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Comments on triangle

What made you want to look up triangle? Please tell us where you read or heard it (including the quote, if possible).


to deposit or conceal in a hiding place

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