# adiabatic

> English word · Adjective · IPA /ˌeɪ.dɪəˈbæt.ɪk/ · frequency rank #59,169

## Definitions
1. Without gain or loss of heat (and thus with no change in entropy, in the quasistatic approximation).
2. Involving the slow change of the Hamiltonian of a system from its initial value to a final value.

## Etymology
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”).

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/adiabatic