Clausius, Annalen 125 (1865), pp. 390 and 400·German

Die Entropie

Clausius already had a quantity S, and a German name for it: Verwandlungsinhalt, the transformation content of a body. He wanted a name that could pass unchanged into every new language. He took Greek ἡ τροπή, which he glosses die Verwandlung, and shaped Entropie so that it would sit beside Energie. Ten pages later the paper closes with two laws. Established wording of the naming and of the maxim. sey, seyn, and constant stay as printed.