Air & Ether

As the Revd. Francis Valpy remarks in the introduction to his Etymological Dictionary of the Latin Language, Latin is intimately connected with Greek and the nature of the connection is not that of sister to sister, but of daughter to mother. In other words, it is sufficient for the etymologist to trace a Latin to a Greek word, rather than needing to proceed to some other language which produced both.

There are two words in Latin for ‘air’, meaning the atmosphere, and both come directly from the Greek and have forms that are peculiarly Greek. They are aer (gen. aeris), meaning the lower air or atmosphere around us, and aether (gen. aetheris), meaning the upper air or ether. They come from ἀηρ and αἰθηρ respectively, both are masculine, and both have accusative singular ending in -a (aera and aethera), which is the accusative singular ending of 3rd-declension masculine and feminine nouns in Greek.