a (1): a condition of being hot :warmth(2): a marked or notable degree of hotness
b: pathological excessive bodily temperature
c: a hot place or situation
d (1): a period of heat (2): a single complete operation of heating; also: the quantity of material so heated
e (1): added energy that causes substances to rise in temperature, fuse, evaporate, expand, or undergo any of various other related changes, that flows to a body by contact with or radiation from bodies at higher temperatures, and that can be produced in a body (as by compression) (2): the energy associated with the random motions of the molecules, atoms, or smaller structural units of which matter is composed
f: appearance, condition, or color of a body as indicating its temperature
Energy transferred from one body to another as the result of a difference in temperature. Heat flows from a hotter body to a colder body when the two bodies are brought together. This transfer of energy usually results in an increase in the temperature of the colder body and a decrease in that of the hotter body. A substance may absorb heat without an increase in temperature as it changes from one phase to anotherthat is, when it melts or boils. The distinction between heat (a form of energy) and temperature (a measure of the amount of energy) was clarified in the 19th century by such scientists as J.-B. Fourier, Gustav Kirchhoff, and Ludwig Boltzmann.