parallelogram

n. four-sided plane figure with the opposite sides parallel and equal

In geometry, a parallelogram is a quadrilateral with two sets of parallel sides. The opposite sides of a parallelogram are of equal length, and the opposite angles of a parallelogram are congruent. The three-dimensional counterpart of a parallelogram is a parallelepiped.
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Noun
1. a quadrilateral whose opposite sides are both parallel and equal in length
(antonym) trapezium
(hypernym) quadrilateral, quadrangle, tetragon
(hyponym) rhombus, rhomb

(n.)
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.
  

n.
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