Latent heat is energy released or absorbed, by a body or a
thermodynamic system, during a constant-temperature process that is specified in some way. An example is latent heat of fusion for a
phase change, melting, at a specified temperature and pressure. The term was introduced around 1762 by
Scottish chemist Joseph Black. It is derived from the Latin
latere (
to lie hidden). Black used the term in the context of
calorimetry where a heat transfer caused a volume change while the thermodynamic system's temperature was constant.