triangle

noun

tri·​an·​gle ˈtrī-ˌaŋ-gəl 

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

• 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

There's also teases of more pod love triangles (of course), social media exposés, lies, and exes potentially still being in the picture (and living in the same building). —Sydney Bucksbaum, EW.com, 28 Jan. 2025

Despite the many love triangles and surprises, and the downright bizarre nature of the show, some people do form genuine connections, and the Love Is Blind successful couples may just stand the test of time. —Whitney Perry, Glamour, 22 Jan. 2025

Holland tried to shake him off, but was unsuccessful and De Ridder established back control with a body triangle, then locked up a rear-naked choke to force the tap and secure a hugely impressive first-round victory. —David Faris, Newsweek, 19 Jan. 2025

The article then suggested that the most detrimental aspect was the right-sided triangle. —Jordan Campbell, The Athletic, 18 Jan. 2025

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

Phrases Containing triangle

• equilateral triangle
• isosceles triangle
• Pascal's triangle
• right-angled triangle
• right triangle
• spherical triangle
• triangle inequality

Kids Definition

triangle

noun

tri·​an·​gle ˈtrī-ˌaŋ-gəl 

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 

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