A weak force of attraction between electrically neutral molecules that collide with or pass very close to each other. The van der Waals force is caused by the attraction between electron-rich regions of one molecule and electron-poor regions of another (the attraction between the molecules seen as electric dipoles). The attraction is much weaker than a chemical bond.
Van Der Waals force is a weak attractive force between atoms or nonpolar molecules caused by an instantaneous dipole moment of one atom or molecule that induces a similar temporary dipole moment in adjacent atoms or molecules.