Meaning

noun a unit of heat equal to the amount of heat required to raise the temperature of one kilogram of water by one degree at one atmosphere pressure; used by nutritionists to characterize the energy-produci

noun unit of heat defined as the quantity of heat required to raise the temperature of 1 gram of water by 1 degree centigrade at atmospheric pressure

originBorrowed from French calorie, formed from Latin calor. It was originally defined as the large calorie in the early 19th century, with the small calorie being defined some decades later.

Etymology from Wiktionary, CC BY-SA 3.0