In thermodynamics, dissipation refers to the process of the loss of mechanical energy or energy in general.
The term "dissipation" was introduced, significantly, in the 1852 article “On a Universal Tendency in Nature to the Dissipation of Mechanical Energy” by British physicist and mathematician William Thomson; a phraseology later to be interpreted as the "law of dissipation of energy"  In Thomson's view, according to “known facts with reference to the mechanics of animal and vegetable bodies” there is “at present in the material world a universal tendency to the dissipation of mechanical energy” and that “any restoration of mechanical energy, without more than an equivalent of dissipation, is impossible in inanimate material processes, and is probably never effected by means of organized matter, either endowed with vegetable life or subject to the will of an animated creature”. This terminology was later employed by Belgian thermodynamicist Ilya Prigogine in his theory of "dissipative structures". 
In the second law work of William Thomson the idea is inferred that the vague idea of the “dissipation of energy” is an alternative yet equivalent to Rudolf Clausius’ “entropy increase” version of the second law of thermodynamics. To this day, the two versions by many are seen as being synonymous. The dissipation of heat, contrary to what Thomson believed, according to science historians Stephen Weininger and Helge Kragh (who cite Edward Daub’s 1970 article “Entropy and Dissipation”), does not correspond to a change in entropy, and in general the dissipation theorem is weaker than the entropy theorem in explaining why some processes occur spontaneously and some do not. 
See also: social friction; human friction; human entropyIn regards to how the physical notion of dissipation translated over into human thermodynamic terminology, the extension is a bit blurry.