Meaning of principle of virtual work

prin'ciple of vir'tual work'

Pronunciation: [key]
— Mech. Mech.
  1. the principle that the total work done by all forces on a system in static equilibrium is zero for a set of infinitesimally small displacements.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.