'balneae' originates from Latin, specifically the word 'balneum', where the root 'balne-' came from Greek 'balaneion' and meant 'bath'.

'balneae' changed from the Greek word 'balaneion' into the Latin 'balneum'; the Latin plural forms 'balnea' and the variant 'balneae' were used for bathing places and were later borrowed into English in scholarly descriptions of Roman baths.

Initially, it meant 'bath' (in Greek and then Latin), and over time it retained that core meaning; in modern English usage it is specialized to refer to Roman or ancient public bathing complexes.