Tetragon

Tetragon is a plane figure with four straight sides and angles.

In geometry a quadrilateral is a four-sided polygon, having four edges (sides) and four corners (vertices).

It is also called a tetragon, derived from Greek “tetra” meaning “four” and “gon” meaning “corner” or “angle”

The only regular (all sides equal and all angles equal) quadrilateral is a square. So all other quadrilaterals are irregular.

In daily life we think of a square as not being a rectangle but in mathematics it is.
A square is a rectangle with equal sides.