antonomasia Definition

antonomasia
noun

1. The use of a title or epithet to address or refer to someone or something rather than using the proper name name, eg the Iron Lady to refer to Margaret Thatcher or Auld Reekie to refer to Edinburgh.
2. The use of someone's name to convey some quality that is associated with that name, eg Gazza in Philip is the Gazza of the primary school football team.

Etymology: 16c: Greek, from onomazein to name.