mesalliance

A mésalliance (also misalliance) is a marriage to an unsuitable partner. Typically used to define a union with a socially inferior partner, like morganatic marriage by a member of royal family, this Gallicism is also used metaphorically, especially in the misalliance variant, to describe a generally unworkable association, for example, the ill-fated alliance of German nobility with Hitler.

Researchers also use terms hypergamy (for "marrying up") and hypogamy ("marrying down") to describe marriages involving partners from different social classes or status. Both terms were invented on the Indian subcontinent in the 19th century while translating classical Hindu law books, which used the Sanskrit terms (a bride is marrying a man from a higher caste) and (husband is from lower caste). The hypergamy and hypogamy can therefore be considered as special cases of mésalliance.