An Etymological Dictionary of the German Language/Annotated/Magen
Magen, masculine, from the equivalent Middle High German and Middle Low German mage, Old High German mago, masculine, ‘stomach’; compare Dutch maag, Anglo-Saxon maga, Middle English mawe, English maw, Old Icelandic mage, Danish mave, ‘stomach’; Gothic *maga (genitive *magins) is wanting. From Teutonic is derived Italian (dialectic) magone, ‘crop (of birds),’ or rather magun, also magon, ‘vexation,’ to which Rhæto-Romance magún, ‘stomach,’ is allied.’ For the early history of the word we have no definite clue; to derive Magen from mögen, root mag, ‘to be able, have strength’ (as if the stomach were the ‘nourishing, strength giving part’), is not to be commended. The names of parts of the body need not, however, be traced back to a verbal root; compare Herz, Niere, and Leber.