An Etymological Dictionary of the German Language/gemein
gemein, adj., ‘common, public; mean, vulgar,’ from MidHG. gemeine, OHG. gimeini, ‘belonging to one another, in common, universal, belonging to the great body’; an adj. common to Teut.; comp. Goth. gamains, ‘in common, joint, general, unholy,’ AS. gemœ̂ne, E. mean, Du. gemeen. The common Teut. ga-maini-s is primit. allied to the equiv. Lat. com-mûnis (for com-moini-s); comp. Lat. ûnus with Goth. ains, Aryan oino-s. Since ‘in common’ is the primary meaning of the class, Meineid (which see) cannot be very closely allied to its OTeut. cognates.