isosceles
Americanadjective
adjective
-
(of a triangle) having two sides of equal length
-
(of a trapezium) having the two nonparallel sides of equal length
Etymology
Origin of isosceles
1545–55; < Late Latin < Greek isoskelḗs with equal legs, equivalent to iso- iso- + skél ( os ) leg + -ēs adj. suffix
Explanation
In geometry, the word isosceles describes a triangle with two sides that are the exact same length. The angles across from each equal side are also the same in an isosceles triangle. Mathematicians use the term isosceles in two slightly different ways. The Greek mathematician Euclid defined an isosceles triangle as having exactly (and only) two equal sides. Modern geometry experts tend to say that a triangle is isosceles if at least two sides are equal — making an equilateral triangle (with three equal sides) also an isosceles triangle. The Greek root, isoskeles, means "with equal legs."
Vocabulary lists containing isosceles
The ACT Math Test: Geometry, List 1
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National Spelling Bee '14: Prelims Round 3
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Geometry - Introductory
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
A sort of isosceles triangle is formed, which will eventually collapse.
From Los Angeles Times ● Apr. 4, 2024
A pentagon is formed by placing an isosceles triangle on a rectangle, as shown in the diagram.
From Textbooks ● Mar. 30, 2016
Arby’s Potato Cakes are lusty little isosceles triangles of pure crunch.
From Washington Post ● Apr. 22, 2015
In the late 16th century, peak beards – beards shaped like an isosceles triangle – had a moment.
From The Guardian ● Aug. 27, 2014
Greek letters move across the undersides of his eyelids: isosceles triangles, betas, sine curves.
From "All the Light We Cannot See" by Anthony Doerr
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Get a wordDefinitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
