Definition of Antonomasia

Antonomasia: 1. The substitution of a title for a proper name, as in addressing a physician as "Doctor" or a nurse as "Nurse."
2. The substitution of a personal name for a noun to designate a member of a group or class, as in calling a geneticist a Mendelist (after Gregor Mendel, who discovered the principles of inheritance).
The word antonomasia is Latin, from the Greek antonomazein, to name instead: anti-, instead of + onomazein, to name (from onoma, name).