[trahy-ang-guh l]


Origin of triangle

1350–1400; Middle English < Latin triangulum, noun use of neuter of triangulus three-cornered. See tri-, angle1
Related formstri·an·gled, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for triangle

Contemporary Examples of triangle

Historical Examples of triangle

British Dictionary definitions for triangle



geometry a three-sided polygon that can be classified by angle, as in an acute triangle, or by side, as in an equilateral triangle. Sum of interior angles: 180°; area: 1/2 base × height
any object shaped like a triangle
any situation involving three parties or points of viewSee also eternal triangle
music a percussion instrument consisting of a sonorous metal bar bent into a triangular shape, beaten with a metal stick
a group of three
Derived Formstriangled, adjective

Word Origin for triangle

C14: from Latin triangulum (noun), from triangulus (adjective), from tri- + angulus corner
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for triangle

late 14c., from Old French triangle (13c.), from Latin triangulum "triangle," from neuter of adj. triangulus "three-cornered," from tri- "three" (see tri-) + angulus "corner, angle" (see angle (n.)).

In the huts of witches all the instruments and implements are triangular. ["Handwörterbuch des deutschen Aberglaubens"]
Online Etymology Dictionary, © 2010 Douglas Harper

triangle in Medicine




A three-sided area, space, or structure.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

triangle in Science



A closed geometric figure consisting of three sides.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Idioms and Phrases with triangle


see eternal triangle.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.