triangular
Americanadjective
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Also: trigonal. of, shaped like, or relating to a triangle; having three corners or sides
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of or involving three participants, pieces, or units
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maths having a base shaped like a triangle
Other Word Forms
Etymology
Origin of triangular
1535–45; < Latin triangulāris, equivalent to triangul ( um ) triangle + -āris -ar 1
Explanation
Anything that looks like a a shape with three sides and three angles is triangular. If you see a triangular fin in the ocean while you’re swimming, watch out! Shark! Start looking for triangular shapes and you'll begin to see them everywhere, from a triangular slice of pizza to a tortilla chip. Like triangle, triangular is rooted in the Latin tri-, "three," and angulus, "angle or corner." You'll also occasionally find this adjective describing things that involve three people, like a triangular relationship between three best friends.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
While removing sheetrock during demolition, workers found remnants of a balcony at the triangular point on the 20th floor, identical to an existing balcony one floor above.
From BBC ● Jul. 26, 2026
The insect can be identified by its flat triangular head, large eyes and clear wings.
From Los Angeles Times ● Jun. 11, 2026
The fancy vivid blue-green diamond is triangular in shape and "the size of the nail on your smallest finger" according to Fawcett.
From Barron's ● May 13, 2026
The researchers reported the first known example of a cyclotrialumane, a compound made of three aluminum atoms arranged in a trimeric -- triangular -- structure.
From Science Daily ● May 1, 2026
A small triangular patch of light illuminates one wall, but darkness paints the rest.
From "The Adoration of Jenna Fox" by Mary E. Pearson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
