first family

Appellatisization of First Family.

first family (plural first families)

1. (generic) A nuclear family that is or was a First Family, when speaking non-specifically.
2. A family of great importance or influence.
   • 1878, Henry James, An International Episode‎:

     They walked up the Fifth Avenue, where, for instance, he had told them that all the first families lived. But the first families were out of town, and our young travelers had only the satisfaction of seeing some of the second—or perhaps even the third—taking the evening air upon balconies and high flights of doorsteps, in the streets which radiate from the more ornamental thoroughfare.