equilateral

American  

[ee-kwuh-lat-er-uhl, ek-wuh-] / ˌi kwəˈlæt ər əl, ˌɛk wə- /

adjective

1. having all the sides equal.

   an equilateral triangle.

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noun

1. a figure having all its sides equal.

2. a side equivalent, or equal, to others.

equilateral British  

/ ˌiːkwɪˈlætərəl /

adjective

1. having all sides of equal length

   an equilateral triangle

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noun

1. a geometric figure having all its sides of equal length

2. a side that is equal in length to other sides

equilateral Scientific  

/ ē′kwə-lăt′ər-əl /

1. Having all sides of equal length, as a triangle that is neither scalene nor isosceles.

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Other Word Forms

Derived Forms

• nonequilaterally
  adverb
• unequilaterally
  adverb
• equilaterally
  adverb
• subequilateral
  adjective
• nonequilateral
  adjective
• unequilateral
  adjective

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.

Related Words

• rectangular