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

His dish looked like an intricate sculpture with lots of triangles. —Buddha Lo, Peoplemag, 11 Apr. 2024

On the western margin, a series of blue triangles along an elevated ridge indicated Ukrainian trenches. —Luke Mogelson, The New Yorker, 8 Apr. 2024

So did Lute Olson, Seth Greenberg and Tex Winter (the architect of the triangle offense). —Mark Zeigler, San Diego Union-Tribune, 2 Apr. 2024

At this point the initial polygon has been reduced to a triangle, whose interior angle sum is known to be 180 degrees. —Patrick Honner, Quanta Magazine, 22 Mar. 2024

The triangle plot is thus established without having to be named, and so is the interconnectedness of love and loss that will emerge as the story’s theme. —Jesse Green, New York Times, 21 Mar. 2024

The point of their little love triangle, the hottie Aaron (Joseph Torres) seems utterly generic. —Karen D'souza, The Mercury News, 20 Mar. 2024

On March 15, Zendaya's longtime creative partner and stylist Law Roach shared a behind-the-scenes look at a shoot for her upcoming tennis love triangle drama, Challengers. —Emily Tannenbaum, Glamour, 16 Mar. 2024

Pulido took on the top of the triangle, giving Sporting a second central attacking player while also dropping back to cover the space between the more defensive midfielders and forward Willy Agada. —Daniel Sperry, Kansas City Star, 29 Mar. 2024

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

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

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