"Energy" is a word with a precise meaning, at least when used in a scientific context, but this was not always so.

Thomas Young (1773-1829) first used "energy" in the modern scientific sense in 1807 to denote what we now call kinetic energy. Young was a pioneer of the physics of light (he also deciphered Egyptian hieroglyphics using the Rosetta stone). Young did not coin the word; he merely adopted a term with a long history in the English language. Starting in the 1580s writers used "energy" to describe a vigorous use of speech or writing. It was borrowed from the Latin and Greek words for "activity."

Over the years, everyday use of the word "energy" came to mean any exercise of power or activity, whether of body, language, or thought. After 1807, when scientists adopted the term "energy," new discoveries called for new terms. The phrase "potential energy" first appeared in the 1850s, followed by "mechanical," "chemical," "electrical," and finally "atomic" energy.