1) form of energy 2) source of energy the physical form in which energy occurs GRM: n. (1,2) USG: the use of the term ''form of energy" generally refers to the physical form in which energy occurs (heat, kinetic energy, electricity), whereas ''source of energy'' generally refers to the potential to release energy (coal,oil) Note: water and hydroelectric power, solid, liquid and gaseous fuels, nuclear energy, solar energy, wind energy, tidal energy, geothermal energy, waste fuels, waste heat, etc.