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

Bikinis: Including a separate top and bottoms, bikinis come in an array of different styles including triangle tops, halters, bandeaux, side-tie bottoms, full briefs, Brazilian tangas, and more. —Andrea Navarro, Glamour, 21 June 2024

Lake Anna State Park includes about 10 miles of shoreline along Lake Anna, a 13,000-acre reservoir in the center of a triangle formed by Charlottesville, Fredericksburg and Richmond. —Jenna Portnoy, Washington Post, 15 June 2024

His hybrid of the triangle offense will be dealt with because teams play each other far more than in college and scouting will stifle it. —Los Angeles Times, 15 June 2024

The plaque, which features the neighborhood’s iconic tulip design, will be unveiled on the triangle at the intersection of Charlotte Street and 27th Terrace. —Natalie Wallington, Kansas City Star, 6 June 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

• 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