Cohesion (v. lat. cohaerere "stick or stay together") or cohesive attraction or cohesive force is a physical property of a subtsance, cause by the intermolecular attraction between like-molecules within a body or substance that acts to unite them. Water, for example, is strongly cohesive due to strong polarity induced by two hydrogen bonds in a tetrahedral configuration. This results in a relatively strong Coulomb force between molecules. Van der Waals gases such as methane, however, have weak cohesion due only to Van der Waals forces that operate by induced polarity in non-polar molecules.