energy-n; 3 Senses

Sense Number 1: the capacity or manifestation of performing work

Commentary: ENERGY[+force][+capacity][+to_perform][+work] (physics) the capacity of a physical system to do work; example units of energy are joules or ergs

The famous equation E=Mc2 asserts an equivalence between an amount of energy and amount of mass.
The rock's potential energy was converted to kinetic energy when it fell off the cliff.
His company is developing alternative energies for heating and transportation.
The investor recommended stocks in the energy and pharmaceutical sectors.
What is the cost of these various energies per hour of usage?

WordNet 2.0 Sense Numbers: 1

Sense Number 2: the quality of acting with vigor and vitality

Commentary: ENERGY[+quality][+behavioral][+vitality] vigor, vigour, vim, vitality - a healthy capacity for vigorous activity

Jogging works off my excess energy.
His writing conveys great energy.
John seems to have no energy these days.
Her staff put enormous energy into the project.

WordNet 2.0 Sense Numbers: 2 3 4 5

Sense Number 3: Dept of Energy

Commentary: ENERGY[+organization][+department][+government][+of_fuel] Department of Energy, Energy Department, Energy, DOE - the federal department responsible for maintaining a national energy policy of the United States

Energy issued a statement urging people in California to decrease electricity consumption during peak hours.
The Department of Energy was created in 1977.

WordNet 2.0 Sense Numbers: 3