The temperature of an object in correct units (Kelvin) is a measure of the average kinetic energy of a single constituent of a system. The temperature 0 K denotes the point where, if a substance remained a gas as it was cooled, the kinetic energy of a single atom would be zero.

The word “heat” is used in physics exclusively to refer to the internal energy that flows from one body to another, across a temperature difference.  The heat capacity, or specific heat capacity, is a parameter unique to each given substance, which allows one to estimate what temperature change ΔT is observed in the system for a given amount of heat Q gained or lost.