(Lat. condensatio), the act by which a body is rendered more dense, compact, or of greater specific gravity, by bringing its particles into closer union. The word is commonly applied to the conversion of vapour into water, by distillation, or by a natural process. Condensation is the reverse of expansion. All matter which is expansible is capable of condensation; and condensation may convert a gas into a liquid, and a liquid into a solid. Hence solidity and increased weight are consequences of condensation. Dew and rain are produced by the condensation of vapour from the air. See Evaporation and Clouds.