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.
1 A square has two pairs of parallel sides, therefore it is a parallelogram; in the figure, we see that $\overline{AB}$ is parallel to $\overline{CD}$ and $\overline{AC}$ is parallel to $\overline{BD}$. 2  A square also has 4 right angles, so therefore it is a rectangle.raw at least two examples and two non-examples of each of the quadrilaterals defined below. 1  Parallelogram: A quadrilateral with 2 pairs of parallel sides. 2  Rectangle: A parallelogram with 4 right angles. 3  Rhombus: A parallelogram with 4 sides with equal length.