- a comparative level of capacity for vigorous activity: The child has a high energy level.
- one of a quantized series of states in which matter may exist, each having constant energy and separated from others in the series by finite quantities of energy.
- a constant value of energy in the distribution of energies among a number of atomic particles
- the energy of a quantum state of a system. The terms energy level and energy state are often used loosely to mean quantum state . This is avoided in precise communication
