Illustration of triangle
- 1 equilateral
- 2 acute
- 3 obtuse
- 4 scalene
- 5 isosceles
- 6 right triangle
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
Example Sentences
She cut the sandwiches into triangles.
Recent Examples on the Web The work, which is a comedic love triangle in the spirit of a TV soap opera, is by composer Douglas Moore. 
Domenica Bongiovanni, The Indianapolis Star, 13 Aug. 2022 In a weird way, this episode is a love triangle of Betty, TBK, and Archie. Samantha Highfill, EW.com, 10 June 2022 For example, Verhoog explains, a triangle becomes a mountain, uncannily synchronized to the eerie music. Liz Tormes, Scientific American, 26 Aug. 2022 There is nothing more satisfying than a celebrity love triangle that really delivers on the fun and the drama. Brittany Spanos, Rolling Stone, 12 Aug. 2022 But that came after Biggio’s two-run single (on which Franchy Cordero overran the ball in left-center) and Tapia’s bases-clearing triple into the triangle. Jayna Bardahl, BostonGlobe.com, 24 July 2022 To the east of Amsterdam’s city center sits Funenpark, a peaceful little quarter shaped like a triangle. Stephanie H. Murray, The Atlantic, 7 July 2022 Consider a triangle, a simple geometric object — what mathematicians call a graph — with three edges and three vertices where the edges meet. New York Times, 5 July 2022 The reason to wake-up early to see it today is because a slim 12% crescent Moon will form a triangle with Venus and the Pleiades. Jamie Carter, Forbes, 19 June 2022 See More
Domenica Bongiovanni, The Indianapolis Star, 13 Aug. 2022 In a weird way, this episode is a love triangle of Betty, TBK, and Archie. Samantha Highfill, EW.com, 10 June 2022 For example, Verhoog explains, a triangle becomes a mountain, uncannily synchronized to the eerie music. Liz Tormes, Scientific American, 26 Aug. 2022 There is nothing more satisfying than a celebrity love triangle that really delivers on the fun and the drama. Brittany Spanos, Rolling Stone, 12 Aug. 2022 But that came after Biggio’s two-run single (on which Franchy Cordero overran the ball in left-center) and Tapia’s bases-clearing triple into the triangle. Jayna Bardahl, BostonGlobe.com, 24 July 2022 To the east of Amsterdam’s city center sits Funenpark, a peaceful little quarter shaped like a triangle. Stephanie H. Murray, The Atlantic, 7 July 2022 Consider a triangle, a simple geometric object — what mathematicians call a graph — with three edges and three vertices where the edges meet. New York Times, 5 July 2022 The reason to wake-up early to see it today is because a slim 12% crescent Moon will form a triangle with Venus and the Pleiades. Jamie Carter, Forbes, 19 June 2022 See More 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
Kids Definition
triangle
noun
tri·an·gle ˈtrī-ˌaŋ-gəl
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
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