Measure of energy is a term used to describe the amount of energy that is present in a system. ENTROPY (7 letters) is a measure of the disorder or randomness of a system, and is often used to measure the energy of a system. ERG (3 letters) is a unit of energy, and is equal to the amount of energy required to move a mass of one gram one centimeter. JOULE (5 letters) is another unit of energy, and is equal to the amount of energy required to move a mass of one kilogram one meter.