noun
morganatic marriage
A marriage between a noble and a commoner in which the commoner spouse and any children do not inherit the noble's titles or property. This is a historical and legal term, not an everyday word.
貴賤結婚では、身分の低い配偶者やその子供は爵位を継承できない。
In a morganatic marriage, the lower-ranking spouse and their children cannot inherit the title.
Compound of 貴賤 (kisen, 'noble and base') and 結婚 (kekkon, 'marriage'). The term is a direct translation of the Western concept of morganatic marriage.