diagonal
in a polygon, a segment that connects nonconsecutive vertices of the polygon
isosceles trapezoid
a trapezoid in which the legs are congruent, both pairs of base angles are congruent, and the diagonals are congruent
kite
a quadrilateral with exactly two distinct pairs of adjacent congruent sides
median
in a trapezoid, the segment that joins the midpoints of the legs
parallelogram
a quadrilateral with parallel opposite sides. Any side of a parallelogram may be called a base
rectangle
a quadrilateral with four right angles
rhombus
a quadrilateral with all four sides congruent
square
a quadrilateral with four right angles and four congruent sides
trapezoid
a quadrilateral with exactly one pair of parallel sides. The parallel sides of a trapezoid are called bases. The nonparallel sides are called legs. The pairs of angles with their vertices at the end points of the same base are called base angles.