Metonymy is the act of referring to a concept not by its name, but by something intimately associated with it. For example when journalists refer to "Washington's response," they mean the political response of the United States. Similarly we see in this example "Palace fury at D-day snub to Queen." Naturally the palace itself is not furious, but it is a symbol that represents the royal family.
Metonymy is closely related to, but should not be confused with synecdoche, which is where one part of something is used to refer to the whole thing.