[ ee-kwuh-lat-er-uh l, ek-wuh- ]
/ ˌi kwəˈlæt ər əl, ˌɛk wə- /


having all the sides equal: an equilateral triangle.


a figure having all its sides equal.
a side equivalent, or equal, to others.

Origin of equilateral

From the Late Latin word aequilaterālis, dating back to 1560–70. See equi-, lateral

Related forms

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for equilateral

British Dictionary definitions for equilateral


/ (ˌiːkwɪˈlætərəl) /


having all sides of equal lengthan equilateral triangle


a geometric figure having all its sides of equal length
a side that is equal in length to other sides

Derived Forms

equilaterally, adverb
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

Science definitions for equilateral


[ ē′kwə-lătər-əl ]

Having all sides of equal length, as a triangle that is neither scalene nor isosceles.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.