equilateral
Americanadjective
noun
-
a figure having all its sides equal.
-
a side equivalent, or equal, to others.
adjective
noun
-
a geometric figure having all its sides of equal length
-
a side that is equal in length to other sides
Other Word Forms
Etymology
Origin of equilateral
From the Late Latin word aequilaterālis, dating back to 1560–70. See equi-, lateral
Explanation
A shape is equilateral if all the sides are the same length. In geometry class, people learn about many shapes, such as triangles and squares. A square is equilateral, because all of its sides are the same length. A rhombus is also equilateral — its sides are also the same length. A triangle can be equilateral too, but not a scalene triangle, which has three sides of different lengths. The word equal should help you remember what equilateral means. You can also use it as a noun for an equilateral shape.
Vocabulary lists containing equilateral
STAAR Grade 5 Mathematics: Geometry — Triangles, Polygons, and Prisms
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
STAAR Grade 8 Mathematics: Geometry and Measurement, List 2
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Geometry, List 2
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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.
For four points you can attach two equilateral triangles along an edge to make a diamond shape with five pairs of points the same distance from each other.
From Slate ● Jun. 22, 2026
Lisa will use the same principle but fire its beams over a much greater distance, and between three identical spacecraft arranged as an equilateral triangle.
From BBC ● Jan. 25, 2024
She added an equilateral oval line, slightly off-center within the disk’s perfect circle.
From Los Angeles Times ● Jan. 6, 2023
The equilateral cross with its legs bent at right angles is a millennia-old sacred symbol in Hinduism, Buddhism and Jainism that represents peace and good fortune.
From Washington Post ● Dec. 2, 2022
It is a variation of the basic principle that if you know one angle and one side of an equilateral or right-angled triangle, then you can determine the other angles and sides.
From "The Invention of Science" by David Wootton
Random Word
Spin the wheel and learn a new word!
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.
