Real Dictionary

joule
countable noun: In physics, a joule is a unit of energy or work.

Joule in American English
James Prescott1818-89; Eng. physicist
the basic unit of energy or work in the SI, MKS systems, equal to the amount of work done by a force of one newton acting through a distance of one meter
noun: the SI unit of work or energy, equal to the work done by a force of one newton when its point of application moves through a distance of one meter in the direction of the force: equivalent to 107ergs and one watt-second

Joule in British English
noun: James Prescott. 1818–89, English physicist, who evaluated the mechanical equivalent of heat and contributed to the study of heat and electricity
noun: the derived SI unit of work or energy; the work done when the point of application of a force of 1 newton is displaced through a distance of 1 metre in the direction of the force. 1 joule is equivalent to 1 watt-second, 107 ergs, 0.2390 calories, or 0.738

joule in Electrical Engineering
noun: A joule is a measurement of energy or work, that, in mechanical systems, is equal to the force of one newton, moving an object a distance of one meter.