Source : Webster's Revised Unabridged Dictionary (1913)

Morganatic \Mor`ga*nat"ic\, a. [LL. matrimonium ad morganaticam,
   fr. morganatica a morning gift, a kind of dowry paid on the
   morning before or after the marriage, fr. OHG. morgan
   morning, in morgangeba morning gift, G. morgengabe. See
   {Morn}.]
   Pertaining to, in the manner of, or designating, a kind of
   marriage, called also {left-handed marriage}, between a man
   of superior rank and a woman of inferior, in which it is
   stipulated that neither the latter nor her children shall
   enjoy the rank or inherit the possessions of her husband.
   --Brande & C. -- {Mor`ga*nat"ic*al*ly}, adv.

Source : WordNet®

morganatic
     adj : (of marriages) of a marriage between one of royal or noble
           birth and one of lower rank; valid but with the
           understanding that the rank of the inferior remains
           unchanged and offspring do not succeed to titles or
           property of the superior [syn: {left-handed}]