Borrowed from Ancient Greek ἔργον (érgon). Doublet of erg and work.
In philosophy, the word is loaned in its capacity as a technical term in Aristotelianism, in English usage following Alexander Grant, The Ethics of Aristotle (1857).
In classical thermodynamics, the term is coined as translating German Werk. Rudolf Clausius (1864) made a technical distinction between Werk and Arbeit, both translating to English "work", and suggested Ergon for the purposes of the translation of his terminology into other modern languages.
The author has used the German word Werk, which is almost synonymous with Arbeit, but proposes the term Ergon as more suitable for introduction into other languages. The Greek word ἔργον is so closely allied to the English word work, that both are quite well suited to designate two magnitudes which are essentially the same, but measured according to different units.
—T.A.H.", T. A. Hirst (trans.), The Mechanical Theory of Heat (1867), Appendix A. to Sixth Memoir , "On Terminology" (translator's note), p. 254.
ergon (uncountable)