An Etymological Dictionary of the German Language/Annotated/Muff

by Friedrich Kluge

Muff (1.), masculine, ‘muff,’ Modern High German only; from Low German muff, Dutch mof, ‘muff,’ English muff; a modern Teutonic word connected with French moufle, ‘mitten,’ Middle Latin (even in the 9th century) muffula. The origin of the cognates has not yet been determined; they are generally connected with Middle High German mouwe, ‘sleeve.’

Muff (2.), ‘mould,’ Middle High German only, allied to Dutch muf, ‘musty, moist, mouldy’; late Middle High German müffeln, ‘to smell bad or rotten.’ With these are connected the widely-diffused Romance cognates, which are said to have originated in the German words: French moufette, ‘firedamp (in mines),’ Italian muffo, ‘mouldy.’