Translation of "Quadrilateral" in Japanese

A parallelogram is a quadrilateral formed from two sets of parallel lines.

平行四辺形は二組の辺が平行している四角形です。

A square is a quadrilateral with four sides the same and where all four corners are right angles.

正方形は４つの辺がすべて等しく、４つの角がすべて直角である四角形です。