Meaning of Raoult's law

Ra•oult's' law'

Pronunciation: (rä-lz'), [key]
— Physical Chem. Physical Chem.
  1. the principle that the fraction by which the vapor pressure of a solvent is lowered by the addition of a nonvolatile, nonelectrolytic solute is equal to the mole fraction of the solute in the solution.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.