Metonymy is a figure of speech where a word or phrase is used to stand in for another word or phrase that is closely related to it. This relation can be based on:
* Cause and effect: "He's got a good head on his shoulders." (Head stands in for intelligence)
* Container and contents: "She drank the whole bottle." (Bottle stands in for the liquid inside)
* Part and whole: "The White House announced a new policy." (White House stands in for the President and his administration)
* Symbol and what it represents: "The crown has spoken." (Crown stands in for the king or queen)
Examples of metonymy:
* The pen is mightier than the sword. (Pen stands in for writing, which represents power)
* Wall Street is worried about the economy. (Wall Street stands in for the financial industry)
* Let's raise a glass to the bride and groom. (Glass stands in for the drink, which represents a toast)
It's important to distinguish metonymy from metaphor, which is a comparison between two unlike things. While metonymy involves a direct transfer of meaning between related things, metaphor involves an indirect comparison.