triangle

noun

tri·​an·​gle ˈtrī-ˌaŋ-gəl How to pronounce triangle (audio)
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

Illustration of triangle

Illustration of triangle
  • 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
In a more lighthearted turn of events, the finale also set up a potential love triangle between Morgan, Karadec, and Tom, the janitor played by JD Pardo. — Randall Colburn, EW.com, 16 Mar. 2025 The proposal also resets relations in the U.S.-Russia-Ukraine triangle, after a heated late February White House clash between Trump and Zelenskyy and the temporary interruption of U.S. military aid to Kyiv seemed poised to thrust Washington deeper into the Kremlin’s orbit. — Ruxandra Iordache, CNBC, 14 Mar. 2025 Now in its third season, the fiery love triangle between Gabriela Perez (Stephanie Arcila), Diego Moreno (Rafael de la Fuente) and Bode Donovan (Max Thieriot) has finally been extinguished. — Samantha Stutsman, People.com, 14 Mar. 2025 The triangle was turned right-side-up to show that gay people were standing up to oppressive forces. — Raja Krishnamoorthi, Newsweek, 13 Mar. 2025 See All Example Sentences for triangle

Word History

Etymology

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

First Known Use

14th century, in the meaning defined at sense 1

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

Phrases Containing triangle

Rhymes for triangle

See All Rhymes for triangle

Browse Nearby Words

triangle
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Cite this Entry

“Triangle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/triangle. Accessed 25 Mar. 2025.

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Kids Definition

triangle

noun
tri·​an·​gle ˈtrī-ˌaŋ-gəl How to pronounce triangle (audio)
1
: a figure that has three sides and three angles : a polygon that has three sides
2
: a percussion instrument made of a steel rod bent into a triangle open at one corner which is played by striking with a metal rod
3
: a drafting instrument consisting of a thin flat right-angled triangle

Medical Definition

triangle

noun
tri·​an·​gle ˈtrī-ˌaŋ-gəl How to pronounce triangle (audio)
: a three-sided region or space and especially an anatomical one see anterior triangle, carotid triangle, femoral triangle, posterior triangle, suboccipital triangle

More from Merriam-Webster on triangle

Nglish: Translation of triangle for Spanish Speakers

Britannica.com: Encyclopedia article about triangle

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