quantitative systems description parameter thermodynamic temperature Temperature is the physical property of a system which underlies the common notions of "hot" and "cold"; the material with the higher temperature is said to be hotter. Temperature is a quantity related to the average kinetic energy of the particles in a substance. The 10th Conference Generale des Poids et Mesures decided to define the thermodynamic temperature scale by choosing the triple point of water as the fundamental fixed point, and assigning to it the temperature 273,16 degrees Kelvin, exactly (0.01 degree Celsius).