Trapezoid

A trapezoid is a geometric figure that lies in a plane. Trapezoids are characterized by having one pair of parallel sides. In general it is probably safe to assume that "one pair" means "exactly one pair," so that parallelograms are not also trapezoids. However, it is not clear that this is a universal mathematical convention.

The two parallel sides of the trapezoid are referred to as the bases of the trapezoid; the other two sides are called the legs.