Word Origin & History. epicene mid-15c., originally a grammatical term for nouns that may denote either gender, from L. epicoenus common, from Gk. Extended sense of characteristic of both sexes first recorded in English c.1600; that of effeminate 1630s.
A parallelogram is a quadrilateral with two pairs of parallel sides. Equivalent conditions are that opposite sides are of equal length; that opposite angles are equal; or that the diagonals bisect each other. Parallelograms also include the square, rectangle, rhombus and rhomboid. Rectangle: all four angles are right angles. 2  An equivalent condition is that the diagonals bisect each other and are equal in length. 3  Informally: a box or oblong (including a square). 4  Square (regular quadrilateral): all four sides are of equal length (equilateral), and all four angles are right angles.
Square. 4 congruent sides. 4 right angles (90Â°). Opposite sides are parallel. All angles are congruent. Trapezoid. Only one pair of opposite sides is parallel. Summary. A quadrilateral is a mathematical name for a four-sided polygon. Parallelograms, squares, rectangles, and trapezoids are all examples of quadrilaterals.ll parallelograms are quadrilaterals, so if it is a parallelogram, it is also a quadrilateral. The correct answer is that all trapezoids are quadrilaterals. You can use the properties of quadrilaterals to solve problems involving trapezoids.