There is no particular name. It need not be a regular polygon - for example, consider a stretched hexagon.
A four-sided polygon with opposite sides parallel and all sides congruent is a square.
A square or a rhombus
A square is a four-sided polygon with two congruent parallel sides.
A square's opposite sides are parallel and all the sides are congruent.
Yes opposite sides are parallel and congruent
A four-sided polygon with opposite sides parallel and all sides congruent is a square.
Any polygon with an even number of sides can have opposite sides that are congruent and parallel.
a trapezoid
Any polygon with 2n sides (n integer) where opposite sides are parallel, will have its opposite angles congruent.
A rectangle is a quadrilateral with opposite sides parallel and congruent and four right angles. If all four sides are congruent, it is a square.
A rectangle is a quadrilateral with opposite sides parallel and congruent and four right angles. If all four sides are congruent, it is a square.
The Opposite Sides Parallel and Congruent Theorem states that if a quadrilateral has a pair of opposite sides that are parallel and congruent, then the quadrilateral is a parallelogram.
A square or a rhombus
No
There are many such shapes. Any polygon with an even number of sides can have opposite sides that meet the above requirements.
It cannot be a quadrilateral because if one pair of opposite sides are congruent and parallel, it is a parallelogram and so the other two sides are also (mutually) congruent and parallel. Any polygon with 5 or more sides will have an irregular form which satisfies these conditions.
A square is a four-sided polygon with two congruent parallel sides.