isosceles

Imagine drawing a triangle. If two of its sides are exactly the same length, you have an isosceles triangle. That is the main use of the word. It comes from Greek roots meaning "equal legs," which fits the two matching sides. You will usually see it in geometry, where people talk about side lengths, angles, and the special properties of this kind of triangle.

The word "isosceles" describes a geometric shape with two equal sides. Most often, it refers to an isosceles triangle, a triangle with at least two sides of the same length. These equal sides are often called the "legs," and the angles opposite them are equal too. This makes the word an important part of basic geometry and a common one in math lessons and textbooks.

You will mostly meet this word in discussions of triangles, but it can also appear in the names of other shapes, such as an isosceles trapezoid, which has equal non-parallel sides. In normal English, though, it is still mainly a geometry word, not a general word for balance or fairness. People do not usually use it to describe debates, stories, or everyday situations.

The word comes from the Greek words isos (equal) and skelos (leg). That history helps explain why it points to equal side lengths. So when you see "isosceles," think first of geometry: a shape, especially a triangle, with two sides that match.