Isoscles
isosceles usually refers to triangles. It means that a triangle has two sides of equal length. Convention varies as to the length of the third side. Some people say it must be longer or shorter than the two other sides. Some people allow that an isosceles triangle can have three sides of equal length.
isosceles is also the plural of two sides of equal lengt in a triangle. The word is therefore a noun as well as an adjective.