Which polygon is not a parallelogram?

Any polygon of MORE than four(4) sides is NOT a parallelogram.

A parallelogram is a tetragon ( four sided figure ) of a very specific type.

The opposite sides are parallel. The opposite sides are the same length.

Other tetragons are Square, Rectangle, Trapezium, Rhombus, Kite and Irregular ( by side length and angle).

The Word 'polygon' means any 2-dimensional figure on 'many' ( any number) of sides.