An Etymological Dictionary of the German Language/Annotated/Hefe
Hefe, feminine, ‘yeast, lees, dregs,’ from Middle High German hęve, hëpfe, masculine and feminine, Old High German hęvo, hëpfo, masculine (from hëppo, hafjo, ‘yeast’); as a substance producing fermentation it is derived from the root haf, literally ‘raising'; hence also Old High German hęvilo, Middle High German hęvel, ‘yeast,’ as well as Anglo-Saxon hœf, Dutch hef, heffe, feminine, ‘yeast’ (see Hebel). Similarly French levain, levûre, are related to lever. Yet Old High German hëpfo can scarcely be referred to the Aryan root kap, ‘to raise.’