An Etymological Dictionary of the German Language/Bärme
Bärme, f., ‘yeast,’ borrowed from the equiv. LG. barme, m., which corresponds to AS. beorma and E. barm. Lat. fermentum (if it does not belong to formus, Gr. θερμός, ‘warm’) is perhaps akin to it. Teut. b, Lat. f, are Aryan bh.