An Etymological Dictionary of the German Language/Annotated/vermählen
vermählen, verb, ‘to marry, unite,’ from late Middle High German vermęhelen, usually męhelen, mahelen, literally ‘to give in marriage to a man,’ also ‘to take to wife,’ whence generally ‘to affiance, betroth.’ The word is usually based on Old High German mahal, ‘hall of justice’ (see Mahl and Gemahl); it is better to proceed from the equivalent Middle High German gemahelen, Old High German gimahalen, which are derivatives of Old High German gimahala, ‘spouse.’ For other details concerning its early history see Gemahl. —