The sides of regular polyhedra are regular polygons, and regular polygons are those for which, in turn, all sides are equal (e.g., triangle, square).
The reason the word is correct is because all regular polyhedra are made up of regular polygons. But here we must take into account a small but very important detail. Regular polyhedra can consist only of homogeneous polygons (i.e., cubes can only come from squares, and so on). In terms of mathematics, regular polyhedra consist of homogeneous polygons.Find out about the properties of these geometric solids here.