The story
- Ancient Greek · derived fromἀδιάβατος“impassable”
- English todayadiabatic
19th-century coinage (introduced by W. J. M. Rankine in the 1860s) based on Ancient Greek ἀδιάβατος (adiábatos, “impassable”), used of terrain (rivers, forests) by Xenophon, from ἀ- (a-, “not”) + διά (diá, “through”) + βατός (batós, “passable”), from βαίνω (baínō, “to go”).
Etymology from Wiktionary, CC BY-SA 4.0.