Triangle

noun

1. A polygon with three sides and three angles.
2. A set square.
3. 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. (cue sports) A triangular piece of equipment used for gathering the balls into the formation required by the game being played.
5. A love triangle.