n. [ Gr. &unr_;; &unr_; parallel + &unr_; to write: cf. F. parallélogramme. See Parallel, and -gram. ] (Geom.) 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. [ 1913 Webster ]
Parallelogram of velocities,
parallelogram of forces,
parallelogram of accelerations,
parallelogram of momenta, etc.
a. Of or pertaining to a parallelogram; parallelogrammic. [ 1913 Webster ]