• synonyms


[ ahy-sos-uh-leez ]
/ aɪˈsɒs əˌliz /


(of a straight-sided plane figure) having two sides equal: an isosceles triangle; an isosceles trapezoid.

Nearby words

isopyre, isorhythm, isorhythmic, isorrhea, isosbestic point, isosceles, isoseismal, isoseismic, isosexual, isosmotic, isosorbide dinitrate

Origin of isosceles

1545–55; < Late Latin < Greek isoskelḗs with equal legs, equivalent to iso- iso- + skél(os) leg + -ēs adj. suffix Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for isosceles

British Dictionary definitions for isosceles


/ (aɪˈsɒsɪˌliːz) /


(of a triangle) having two sides of equal length
(of a trapezium) having the two nonparallel sides of equal length

Word Origin for isosceles

C16: from Late Latin, from Greek isoskelēs, from iso- + skelos leg
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 isosceles



"having two equal sides," 1550s, from Late Latin isosceles, from Greek isoskeles "with equal sides," from isos "equal" (see iso-) + skelos "leg" (see scalene).

Online Etymology Dictionary, © 2010 Douglas Harper

Science definitions for isosceles


[ ī-sŏsə-lēz′ ]

Of or relating to a geometric figure having at least two sides of equal length.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.