triangle

1. (geometry) A polygon with three sides and three angles.Examples: "The wedge-shaped character was the triangle, the archaic Paleolithic sign of the vulva; the pubic triangle was at the end of the phallic stylus."Synonyms: threeside, trigon

2. (US, Canada) A set square.CanadaUS

3. (music) A percussion instrument made by forming a metal rod into a triangular shape which is open at one angle. It is suspended from a string and hit with a metal bar to make a resonant sound.

4. (billiards) A triangular piece of equipment used for gathering the balls into the formation required by the game being played.

5. (systemics) The structure of systems composed with three interrelated objects.

6. (historical, usually in the plural) A frame formed of three poles stuck in the ground and united at the top, to which people were bound for corporal punishment.Examples: "I was flogged in 1840. To this day I feel a pain in the chest from the triangles."; "But nothing is said as to what we are to do with the negro when we have cut him off from absolute dominion; we are not informed if we may spread him on the triangles as aforetime;"historicalplural-normally