1. An additional name or epithet.
2. A figure of speech that consists of substituting the name of a thing for something closely related.
3. A rhetorical or stylistic device in which one thing is named or referred to by the name of another related thing; for example. the use of "White House" when referring to the presidential administration of the United States; as well as, "the Crown" referring to a monarchy, "the bottle" referring to alcohol: "He just got himself off the bottle after years of trying to control his alcoholism."