1650s, "dissolution," from Latinized form of Greek katalysis "dissolution, a dissolving" (of governments, military units, etc.), from katalyein "to dissolve," from kata- "down" (or "completely"), see cata-, + lyein "to loosen" (see lose). Chemical sense "change caused by an agent which itself remains unchanged" is attested from 1836, introduced by Swedish chemist Jöns Jakob Berzelius (1779-1848).