(symbol: cal) n. the amount of energy required to raise the temperature of 1 g of water by 1 °C. For most purposes, the calorie (a c.g.s. unit) has been replaced by the SI unit of work and energy, the joule: 1 cal = 4.1868 J. However, the energy values of foods are sometimes still expressed in kilocalories (or Calories [Cal]: 1 Cal = 1,000 cal).