Triangle

1. noun

   any of various triangular drafting instruments used to draw straight lines at specified angles

2. noun

   a percussion instrument consisting of a metal bar bent in the shape of an open triangle

3. noun

   a small northern constellation near Perseus between Andromeda and Aries

   Similar: triangulum

4. noun

   something approximating the shape of a triangle

   “the coastline of Chile and Argentina and Brazil forms two legs of a triangle”