- parallelogram of momenta
- Parallelogram Par`al*lel"o*gram, n. [Gr. ?; ? parallel + ? to
write: cf. F. parall['e]logramme. 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. (Mech.), a parallelogram the diagonal of which represents the resultant of two velocities, forces, accelerations, momenta, etc., both in quantity and direction, when the velocities, forces, accelerations, momenta, etc., are represented in quantity and direction by the two adjacent sides of the parallelogram. [1913 Webster]

*The Collaborative International Dictionary of English.
2000.*