A four-sided polygon with opposite sides parallel and all sides congruent is a square.
There is no particular name. It need not be a regular polygon - for example, consider a stretched hexagon.
A square or a rhombus
A square is a four-sided polygon with two congruent parallel sides.
A square and a rectangle both fit the description
trapezoid
Any polygon with an even number of sides can have opposite sides that are congruent and parallel.
Any polygon with 2n sides (n integer) where opposite sides are parallel, will have its opposite angles congruent.
a trapezoid
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.
There is no particular name. It need not be a regular polygon - for example, consider a stretched hexagon.
No
A quadrilateral
A four sided polygon where the opposite sides are parallel to each other (they must also by congruent). This also makes the opposite angles congruent. __ /_/ Sort of like that.
A square or a rectangle
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 or a rhombus