noun
: a hypothetical temperature characterized by complete absence of heat:
a. on the Kelvin scale : approximately -273.15° C or -459.67° F at which no heat for performance of work could be derived
b. on the scale of the constant-volume hydrogen thermometer : approximately -273.03° C at which hydrogen pressure would become zero if a linear temperature-pressure relation were maintained
c. in classical kinetic theory : a point at which mutual linear motions of all the molecules of a substance would cease