What is meant by the term "Morganatic marriage"?

Morganatic marriage, sometimes called a left-handed marriage, is a marriage between people of unequal social rank, which in the context of royalty prevents the passage of the husband's titles and privileges to the wife and any children born of the marriage.

Generally, this is a marriage between a man of high birth (such as from a reigning, deposed or mediatised dynasty) and a woman of lesser status (such as a daughter of a low-ranked noble family or a commoner). Usually, neither the bride nor any children of the marriage have a claim on the bridegroom's succession rights, titles, precedence, or entailed property. The children are considered legitimate for all other purposes and the prohibition against bigamy applies. In some countries, a woman could also marry a man of lower rank morganatically.

Morganatic, already in use in English by 1727 (according to the Oxford English Dictionary), is derived from the medieval Latin "morganaticus" from the Late Latin phrase (matrimonium ad morganaticam) and refers to the gift given by the groom to the bride on the morning after the wedding, the morning gift, i.e., dower.

The morning gift has been a customary property arrangement for marriage found first in early medieval German cultures (such as the Lombards) and also among ancient Germanic tribes, and the church drove its adoption into other countries in order to improve the wife's security by this additional benefit.