An Etymological Dictionary of the German Language/Annotated/schlürfen

by Friedrich Kluge

schlürfen, verb, ‘to sip, lap, drink,’ Modern High German only; probably, however, its non-occurrence in earlier High German is only an accident (Middle High German *slürfen, Old High German *slurfen); according to the High German permutation Dutch slurpen, ‘to sip,’ is allied. The stem is not found elsewhere; its origin is obscure.