An Etymological Dictionary of the German Language/Annotated/schwätzen

by Friedrich Kluge

schwätzen, verb, ‘to chatter, prate, gossip,’ from the equivalent Middle High German swętzen, allied to Middle High German swaz (tz), ‘talking, chattering’; an intensive form of a Teutonic root swaþ. Compare Middle High German swadern, swatern, ‘to chatter, rustle, clatter,’ of which the simply Modern High German schwadronieren is a Romance derivative. There is no relation to Latin suadere. Origin obscure.