'balneophysiology' originates from modern English coinage combining classical roots: Latin 'balneum' (from Latin; ultimately Greek 'balaneion') meaning 'bath' and Greek 'physis' + 'logos' meaning 'nature' + 'study' (i.e., 'physiology' = study of natural bodily functions).

'balneophysiology' developed as a compound term in medical and spa-science literature in the 19th–20th centuries by joining 'balneology' (the study of baths) and 'physiology' (the study of bodily functions), creating a more specific term referring to physiological effects of bathing.

Initially tied broadly to the study and use of therapeutic baths ('balneology'), the compound came to emphasize physiological mechanisms and measurable bodily effects—hence the current focus on 'physiological effects of baths.'