Metonym is a noun that refers to a metaphoric substitute.

The Greek word metonumia (MET oh me ah) means ‘change of name.’ Another way to think of a metonym is to think of it as a substitute word. For example, when we use the term ‘Washington DC’ to refer to the federal government, we are using a substitute — or a metonym. Here’s an example:

I think I confused my family when I told them my business was going to the dogs. I was using a metonym, but they thought I was working at a dog kennel.