isos·​ce·​les | \ ī-ˈsä-sə-ˌlēz How to pronounce isosceles (audio) , -ˈsäs-ˌlēz \

Definition of isosceles

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,, 26 May 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'isosceles.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of isosceles

1551, in the meaning defined at sense 1

History and Etymology for isosceles

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.

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The first known use of isosceles was in 1551

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Dictionary Entries Near isosceles



isosceles trapezoid

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Last Updated

23 Aug 2022

Cite this Entry

“Isosceles.” Dictionary, Merriam-Webster, Accessed 25 Sep. 2022.

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Nglish: Translation of isosceles for Spanish Speakers


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