- a plane figure with three straight sides and three angles；a thing shaped like a triangle
noun: triangle, plural noun: triangles
- 1. a plane figure with three straight sides and three angles an equilateral triangle
- ▪ a thing shaped like a triangle a small triangle of grass
- ▪ a situation involving three people or things, especially an emotional relationship involving a couple and a third person with whom one of them is involved.
- ▪ a musical instrument consisting of a steel rod bent into a triangle and sounded by being struck with a small steel rod.
- ▪ a frame used to position the balls in pool and snooker.
- ▪ a drawing instrument in the form of a right triangle.
- ▪ a frame of three halberds joined at the top to which a soldier was bound for flogging.