Energy is a fundamental concept in physics, and it is necessary to have a consistent unit to describe it. The most common unit of energy is Joule (J), however, there are other units that are synonyms to it. Some synonyms for the unit of energy include watt-hour (Wh), calorie (cal), kilocalorie (kcal), electronvolt (eV), British thermal unit (BTU), and foot-pound (ft-lb). These synonyms are used in different fields and contexts, depending on the type of energy being measured. For instance, the watt-hour is commonly used in electricity bills, while the calorie is used in food, nutrition, and exercise science. Having knowledge of the different synonyms for the unit of energy is important for accurate measurements in different applications.