1. alien-not contained in or deriving from the essential nature of something; an economic theory alien to the spirit of capitalism; the mysticism so foreign to the French mind and temper; jealousy is foreign to her nature. foreign.
1 the quality of being hot; hotness: in physics, heat is considered a form of energy existing as the result of the random motion of molecules and is the form of energy that is transferred between bodies as a result of their temperature difference.  much hotness; great warmth: stifling heat.
Definition of critical temperature. 1a : the temperature of a substance in its critical state : the highest temperature at which it is possible to separate substances into two fluid phases (vapor and liquid) b : the transition temperature of a solid from one allotropic form to another (as the Curie point of a metal) 2 : transformation temperature.