isosceles

adjective

isos·​ce·​les ī-ˈsä-sə-ˌlēz 

-ˈsäs-ˌlēz

1

of a triangle : having two equal sides see triangle illustration

2

of a trapezoid : having the two nonparallel sides equal

Examples of isosceles in a Sentence

Recent Examples on the Web

Geographically, Richland, Hammonton, and Absecon don't form an isosceles triangle. —Phil Anastasia, Philly.com, 26 May 2017

Word History

Etymology

borrowed from Late Latin isoscelēs, borrowed from Greek isoskelḗs "having equal legs, (of a triangle) having two equal sides, (of numbers) divisible into equal parts, even," from iso- iso- + -skelēs, adjective derivative of skélos (neuter s-stem) "leg," going back to an Indo-European base *skel- "bent," whence also Armenian šeł "slanting, crooked"; with o-grade, Greek skoliós "bent, crooked, askew, devious"; perhaps with a velar extension Germanic *skelga-/*skelha-, whence Old English sceolh "oblique, wry," Old Frisian skilich "squinting," Old High German skelah "crooked, oblique," Old Icelandic skjalgr "wry, oblique"

Note: The Indo-European etymon is also conventionally compared with Latin scelus "misfortune resulting from the ill will of the gods, curse, wicked or accursed act, crime, villainy," a neuter s-stem that appears to match exactly Greek skélos, though if "crime" is secondarily developed from a sense "misfortune," with religious connotations, a connection with crookedness is less likely.

First Known Use

1551, in the meaning defined at sense 1

Phrases Containing isosceles

• isosceles triangle

Kids Definition

isosceles

adjective

isos·​ce·​les ī-ˌsäs-(ə-)ˌlēz 

1

: being a triangle with two equal sides

2

: being a trapezoid whose two nonparallel sides are equal