| Noun | 1. | heat of transformation - heat absorbed or radiated during a change of phase at a constant temperature and pressure heat, heat energy - a form of energy that is transferred by a difference in temperature heat of condensation - heat liberated by a unit mass of gas at its boiling point as it condenses into a liquid; "the heat of condensation is equal to the heat of vaporization" heat of fusion - heat absorbed by a unit mass of a solid at its melting point in order to convert the solid into a liquid at the same temperature; "the heat of fusion is equal to the heat of solidification" heat of solidification - heat liberated by a unit mass of liquid at its freezing point when it solidifies heat of sublimation - heat absorbed by a unit mass of material when it changes from a solid to a gaseous state heat of vaporisation, heat of vaporization - heat absorbed by a unit mass of a material at its boiling point in order to convert the material into a gas at the same temperature |