morganatic

Pertaining to, in the manner of, or designating, a kind of marriage, called also <i>left-handed marriage</i>, 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.

adjective

Source: webster1913

(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

adj.all

Source: WordNet 3.0