In the history of thermodynamics, thermo-dynamic, a conjunction of the parts 'thermo-' (1663) and '-dynamic' (1827), is a term used in 1849 by Scottish mathematical physicist William Thomson in reference to a Carnot engine, one that is reversible. Specifically, in a paper titled paper An Account of Carnot's Theory of the Motive Power of Heat, he states: [1]

"A perfect thermo-dynamic engine is such that, whatever amount of mechanical effect which it might produce? Nothing can be lost in the operations of nature—no energy can be destroyed."

Thomson would later go on to be the first to coin the term "thermo-dynamics" as a subject in 1854.

References
1. Thomson, William. (1849). “An Account of Carnot’s Theory of the Motive Power of Heat – with Numerical Results Deduced from Regnault’s Experiments on Steam”, (127-203) Transactions of the Edinburgh Royal Society, xiv.; Annales de Chime, xxxv. 1852.

External links
● Thermodynamic explained (2 articles) – Helium.com.