Definition of: triangle

(trī′ang′gəl) noun
1. Geom. A figure, especially a plane figure, bounded by three sides, and having three angles.
2. Something resembling such a figure in shape or arrangement.
3. A flat drawing implement for making parallel or diagonal lines, etc.
4. A group or set of three; a triad.
5. A situation involving three persons: the eternal triangle.
6. Music A musical instrument of percussion, consisting of a resonant bar bent into a triangle and open at one corner, sounded by being struck with a small metal rod. [<OF <L triangulum <triangulus three–cornered <tri- three + angulus an angle]
TRIANGLE
a. Scalene. b. Isosceles. c. Equilateral. d. Right–angled. e. Obtuse.