isosceles trapezoid	A trapezoid with one pair of parallel sides and another pair of opposite sides that are congruent.
parallelogram	A quadrilateral with two pairs of parallel sides.
polygon	A closed plane figure with three or more straight sides.
quadrilateral	A four-sided polygon.
rectangle	A quadrilateral with two pairs of parallel sides and four right angles.
rhombus	A quadrilateral with four congruent sides.
square	A quadrilateral whose sides are all congruent and which has four right angles.
trapezoid	A quadrilateral with one pair of parallel sides.