calorie

the word 'calorie' entered english in the mid-19th century from french 'calorie', which was itself a scientific formation from latin 'calor', meaning 'heat'. the latin 'calor' derives from the verb 'calēre', 'to be hot', a term traceable to the proto-indo-european root kele-, meaning 'warm'. the logic of the term is direct: the unit was originally defined as the amount of heat needed to raise the temperature of one gram of water by one degree celsius, thus linking the ancient concept of heat to a modern scientific measurement of energy.

Structure: calor (heat) + ie (noun suffix) calor is a latin root meaning 'heat'. ie is a noun-forming suffix of french origin, often used to form names of units or concepts.