What is a trapezoid also called a parallelogram?

A trapezoid is not typically referred to as a parallelogram; they are distinct types of quadrilaterals. A trapezoid (or trapezium in some regions) has at least one pair of parallel sides, while a parallelogram has both pairs of opposite sides parallel. In summary, while all parallelograms are trapezoids, not all trapezoids are parallelograms.