Definitions for "Parallelogram"
A right-lined quadrilateral figure, whose opposite sides are parallel, and consequently equal; -- sometimes restricted in popular usage to a rectangle, or quadrilateral figure which is longer than it is broad, and with right angles.
A quadrilateral with opposite sides that are parallel
A quadrilateral with 2 pairs of parallel sides, 2 pairs of equal angles, and 2 pairs of equal sides.