a figure bounded by three lines, and containing three angles.-an instrument of percussion, usually made of a rod of steel, bent into the form of a triangle, open at one angle, and sounded by being struck with a small metallic rod.-a draughtsman's square in the form of a right-angled triangle.-a kind of frame formed of three poles stuck in the ground and united at the top, to which soldiers were bound when undergoing corporal punishment, -- now disused.-a small constellation situated between aries and andromeda.-a small constellation near the south pole, containing three bright stars.