triangle

[ trahy-ang-guhl ]

noun

1. a closed plane figure having three sides and three angles.
2. a flat triangular piece, usually of plastic, with straight edges, used in connection with a T square for drawing perpendicular lines, geometric figures, etc.
3. any three-cornered or three-sided figure, object, or piece:

   a triangle of land.

4. a musical percussion instrument that consists of a steel triangle, open at one corner, that is struck with a steel rod.
5. a group of three; triad.
6. a situation involving three persons, especially one in which two of them are in love with the third.
7. Triangle, Astronomy. the constellation Triangulum.

triangle

/ ˈtraɪˌæŋɡəl /

noun

1. geometry a three-sided polygon that can be classified by angle, as in an acute triangle, or by side, as in an equilateral triangle. Sum of interior angles: 180°; area: 1 2 base × height
2. any object shaped like a triangle
3. any situation involving three parties or points of view See also eternal triangle
4. music a percussion instrument consisting of a sonorous metal bar bent into a triangular shape, beaten with a metal stick
5. a group of three

triangle

/ trī′ăng′gəl /

1. A closed geometric figure consisting of three sides.

Derived Forms

• ˈtriˌangled, adjective

Other Words From

• triangled adjective

Word History and Origins

Origin of triangle¹

First recorded in 1350–1400; Middle English, from Latin triangulum, noun use of neuter of triangulus “three-cornered”, tri-, angle ¹

Word History and Origins

Origin of triangle¹

C14: from Latin triangulum (noun), from triangulus (adjective), from tri- + angulus corner

Idioms and Phrases

see eternal triangle .

Example Sentences

For example, you can change drawing A into drawing B by flipping the triangle made by nodes 1, 2 and 3 over the edge connecting nodes 2 and 3.

From Quanta Magazine

A triangle with sides of all different lengths is “scalene,” or “unequal.”

From Nautilus

There is the classic triangle, a sturdy square, and you may even see some rectangular shapes if you are dealing with a nice flatbread.

From Popular-Science

For the four Platonic solids built out of squares or equilateral triangles — the cube, tetrahedron, octahedron and icosahedron — mathematicians recently figured out that the answer is no.

From Quanta Magazine

Like the triangle and the quadrilateral, the N-gon with the maximum area was a regular N-gon, with equal side lengths and angles.

From FiveThirtyEight

This Texas Triangle now has the same population as the entire State of Florida.

From The Daily Beast

The scorned party in a love-triangle, he blew his head off while serving overnight tower duty in 2007.

From The Daily Beast

For her first film, she played a woman caught in a love triangle between a nightclub owner and a country boy.

From The Daily Beast

We kept joking about the show evolving and blossoming from this love triangle into this five-pointed star.

From The Daily Beast

In reading about ASHA, its current location is hard to overlook—Research Triangle, North Carolina.

From The Daily Beast

On the other hand, the arrows along the sides of the triangle represent actual circulation.

From Project Gutenberg

He was a narrow-headed man with frail-looking sloped shoulders and a thin triangle of face.

From Project Gutenberg

There are sixty thousand acres of mighty good spruce in that triangle between us, and it's as good as ours.

From Project Gutenberg

(e) No part of the counter shall intersect a triangle or the produced perpendicular thereof shown on p. 186.

From Project Gutenberg

A third game was called trign, and was played by three persons, stationed at the angles of an equilateral triangle.

From Project Gutenberg

Related Words

• adultery
• affair
• courtship
• dalliance
• devotion
• fling
• flirtation
• infidelity
• involvement
• liaison
• love
• passion
• relationship
• tryst