isosceles

adjective
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, Philly.com, 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.

Learn More About isosceles

Time Traveler for isosceles

Time Traveler

The first known use of isosceles was in 1551

See more words from the same year

Dictionary Entries Near isosceles

isosafrole

isosceles

isosceles trapezoid

See More Nearby Entries 

Statistics for isosceles

Last Updated

23 Aug 2022

Cite this Entry

“Isosceles.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/isosceles. Accessed 25 Sep. 2022.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

More from Merriam-Webster on isosceles

Nglish: Translation of isosceles for Spanish Speakers

WORD OF THE DAY

Test Your Vocabulary

Words Named After People

  • name tags
  • Namesake of the leotard, Jules Léotard had what profession?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Universal Daily Crossword

A daily challenge for crossword fanatics.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!