polygon of forces

Wiktionary

1. n. mechanics A polygonal figure the sides of which are vectors representing several forces acting simultaneously upon one point, so that the vector necessary to make the figure closed is the resultant of those forces.

GNU Webster's 1913

1. n. (Mech.) a polygonal figure, the sides of which, taken successively, represent, in length and direction, several forces acting simultaneously upon one point, so that the side necessary to complete the figure represents the resultant of those forces. Cf. Parallelogram of forces, under Parallelogram.