(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.
(cue sports) A triangular piece of equipment used for gathering the balls into the formation required by the game being played.
(systemics) The structure of systems composed with three interrelated objects.
A draughtsman's square in the form of a right-angled triangle.
(historical) A frame formed of three poles stuck in the ground and united at the top, to which soldiers were bound when undergoing corporal punishment.