This would be a parallelogram or a rhombus. A parallelogram is like a pushed over rectangle and a rhombus a pushed over square. All sides are equal length and parallel on a rhombus but opposite sides are equal and parallel on a parallelogram. None of the sides are joined by 90 degree angles.
Square
If both pairs of opposite sides are the same length, and both pairs of opposite angles are the same, the quadrilateral is a parallelogram (rhombus, rectangle, or square).
square
Parallelogram. You could also call it a rhombus if all sides are the same length, but a rhombus is technically a parallelogram.
A parallelogram.
rhombus. The rhombus is a quadrilateral with all sides equal in length. It is also a parallelogram, so opposite sides are parallel and equal in length, and opposite angles are equal.
Square
QUADRILATERAL
If both pairs of opposite sides are the same length, and both pairs of opposite angles are the same, the quadrilateral is a parallelogram (rhombus, rectangle, or square).
A Rhombus
square
Parallelogram. You could also call it a rhombus if all sides are the same length, but a rhombus is technically a parallelogram.
Most quadrilaterals do not have opposite sides which are equal in length. Sadly, there is no special name for them.
A Rectangle
a pentagon
A parallelogram.
A parallelogram.
I am a rhombus. I don't need to prove that my opposite sides are parallel. If I'm a quadrilateral with four sides that are the same length, then I am definitely a rhombus.