heat of fusion

noun

, Physics.

1. the heat absorbed by a unit mass of a given solid at its melting point that completely converts the solid to a liquid at the same temperature: equal to the heat of solidification.

heat of fusion

1. The amount of heat required to convert a solid at its melting point into a liquid without an increase in temperature. Liquids release the same amount of heat when they solidify.
2. See also heat of vaporization