first family

plural first families

1. genericA nuclear family that is or was a First Family, when speaking non-specifically.
2. A family of great importance or influence.

   1 more example

   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.

   1878, Henry James, An International Episode

1. The family of the President of the United States.
2. broadlyThe immediate family of a political chief executive.