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.
Medical Definition of thermal. 1  1: of, relating to, or caused by heat tactile and thermal senses. 2  2: being or involving a state of matter dependent upon temperature thermal agitation of molecular structure.