A unit of energy is a measure of the amount of energy contained in a given system. The most common units of energy are the CALORIE (7 letters), ERG (3 letters), BUNDLE (6 letters), JOULE (5 letters), QUANTUM (7 letters), mev (3 letters), and watt (4 letters). The CALORIE is a unit of energy used to measure the amount of energy contained in food, while the ERG is a unit of energy used to measure the amount of work done by a force. The BUNDLE is a unit of energy used to measure the amount of energy released by a nuclear reaction, while the JOULE is a unit of energy used to measure the amount of work done by a force over a distance. The QUANTUM is a unit of energy used to measure the amount of energy contained in a single particle, while the mev is a unit of energy used to measure the amount of energy released by a nuclear reaction. Finally, the watt is a unit of energy used to measure the rate of energy transfer.