Thermodynamic may sound complicated and incomprehensible, in fact the first sentence in Wikipedia under Thermodynamics is: a branch of natural science concerned with heat and its relations to energy and work.
It continues with: It defines macroscopic variables (such as temperature, internal energy, entropy, and pressure) that characterize materials and radiation, and explains how they are related and by what laws they change with time. All this may sound perfectly normal for scientists, but for the majority of us it may be a little (wee) bit difficult to grasp.
