1. A three-sided polygon
   "A triangle is the simplest form of a trilateral";
   - trigon, trilateral
    
2. Something approximating the shape of a triangle
   "the coastline of Chile and Argentina and Brazil forms two legs of a triangle"
    
3. [N. Amer] Any of various triangular drafting instruments used to draw straight lines at specified angles
   "The architect used a 45-degree triangle to draw perfect right angles on the blueprint";
   - set square [Brit]
    
4. A percussion instrument consisting of a metal bar bent in the shape of an open triangle
   "The musician delicately struck the triangle, adding a bright, tinkling sound to the orchestral piece"

1. A small northern constellation near Perseus between Andromeda and Aries
   - Triangulum

Derived forms: triangles

Type of: constellation, drafting instrument, form, percussion instrument, percussive instrument, polygon, polygonal shape, shape

Encyclopedia: Triangle, Virginia