- a geometric figure having three angles and three sides
- any three-sided or three-cornered figure, area, object, part, etc.
- a right-angled, flat, triangular instrument used in drawing geometric figures
- a situation involving three persons, esp. when one person is having love affairs with two others
- a musical percussion instrument consisting of a steel rod bent into a triangle with one angle open: it produces a high-pitched, tinkling sound when struck with a short steel rod
Origin of triangleMiddle English from Middle French from Classical Latin triangulum: see tri- and angle