tri·an·gle / ˈtrīˌanggəl/ • n. a plane figure with three straight sides and three angles: an equilateral triangle. ∎  a thing shaped like such a figure: a small triangle of grass. ∎  a situation involving three people or things, esp. 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. ∎  (triangles) hist. a frame of three halberds joined at the top to which a soldier was bound for flogging.

triangles

triangle three-sided figure. XIV. — (O)F. triangle or L. triangulum, sb. use of n. of triangulus three-cornered, f. TRI- + angulus ANGLE2.
So triangular XVI. — late L.; see -AR.

triangle. Perc. instr. of indefinite pitch, made of metal shaped into a triangle and struck with metal stick to give tinkling sound. Much used by composers to intensify excitement, e.g. in 3rd movt. of Brahms's 4th sym. Liszt's pf. conc. No.1 in E♭ has important part for triangle.

triangle (try-ang-ŭl) n. (in anatomy) a three-sided structure or area; for example, the femoral triangle.

Triangle

a set of three.

Example : long wavering triangle of waterfowl, 1895.