antonomasy
noun[Gr. name.]
To use of the name of some office, dignity, profession, science or trade, instead of the true name of the person; as when his majesty is used for a king, lordship for a nobleman. Thus instead of Aristotle, we say, the philosopher; a grave man is called a Cato; an eminent orator, a Cicero; a wise man, a Solomon. In the latter examples, a proper name is used for an appellative; the application being supported by a resemblance in character.