A square or a rhombus
A four-sided polygon with four congruent sides and four equal angles is a square
a square...
it is called a square
A polygon with four sides that has equal opposite sides parallel and four equal angles is called a rectangle. In a rectangle, opposite sides are both equal in length and parallel, while each of the four angles measures 90 degrees. If all four sides are also equal in length, the rectangle becomes a square.
A rhombus is by definition a polygon with four sides of equal length. Since the sum of the internal angles of a polygon with four sides is 360° , a polygon with four sides can have four angles all equal to 90°. In this case we have a particular type of rhombus called square.
A polygon with four equal angles and sides is a square.
It's called a rhombus.
There are many such shapes and there is no specific name.
rectangle
Quadrilateral has four sides and a polygon has 4 equal sides
trapezoid
a parallelogram