TRIANGLE

noun Etymology: Middle English, from Anglo-French, from Latin triangulum, from neuter of triangulus triangular, from tri- + angulus angle Date: 14th century a polygon having three sides, 2. a percussion instrument consisting of a rod of steel bent into the form of a ~ open at one angle and sounded by striking with a small metal rod, a drafting instrument consisting of a thin flat right-angled ~ of wood or plastic with acute angles of 45 degrees or of 30 degrees and 60 degrees, a situation in which one member of a couple is involved in a love affair with a third person