Word: Metonym

You Pronounce it: [met-uh-nim] IPA:ˈmɛtənɪm

Definition: 

1. A word, name, or expression used as a substitute for something else with which it is closely associated. For example, Washington is a metonym for the US government.

Origin:

1830-40; back formation from metonymy

I heard it:

In class, the professor asked us to answer a question and used the word “metonym” in the sentence.

Works Cited:

http://dictionary.reference.com/browse/metonym

http://www.oxforddictionaries.com/definition/english/metonym