That temperature at which a single, pure solid changes phase to a liquid or to a liquid plus another solid phase, upon the addition of heat at a specific pressure. Unless otherwise specified, melting points are usually stated in terms of 1 kPa. The term can also be used for the isothermal melting of certain mixtures, such as eutectic mixtures. Erroneously used also to refer to the temperature at which some appreciable but unspecified amount of liquid develops in a complex solid mixture that possesses a melting range; e.g., the melting point of granite. Abbrev.: mp or MP.