A kite.
Because the diagonals in a square are at right angles to one another!
It is a rhombus whose diagonals are perpendicular and meeting each other at right angles.
Square, rhombus and a kite quadrilateral
A kite.
A Quadrilateral Kite!
If you are not a square then you are a rectangle.
rhombus
kkk
Two pairs of touching sides are the same length. The diagonals meet at right angles. Opposite sides are not parallel.
A trapezoid Trapezoid - 2 congruent diagonals that do not bisect each other. No right angles and has 1 pair of opposite parallel sides.
Rhombus and square are the only quadrilaterals whose diagonals bisect the angles of the quadrilateral. In both these quadrilaterals, the diagonals intersect at right angles, dividing each angle into two equal parts.
Four straight sides, four right angels, diagonals that bisect one another.