morganatic       
adjective uk/ˌmɔː.ɡəˈnæt.ɪk / us/ˌmɔːr.ɡəˈnæt̬.ɪk/
 贵贱通婚的
A morganatic marriage is one in which one partner is of higher social rank, and the other cannot claim this partner's title or possessions or pass them to their children.
  a morganatic marriage/union 贵贱通婚/成婚 
 the Archduke Franz Ferdinand's morganatic wife, Sophie Chotek 弗朗兹·斐迪南大公爵地位较低的妻子索菲·霍泰克