Synecdoche:
a literary device in which a part of something represents the whole or it may use a whole to represent a part.
Synecdoche may also use larger groups to refer to smaller groups or vice versa. It may also call a thing by the name of the material it is made of or it may refer to a thing in a container or packing by the name of that container or packing.
Metonymy:
a literary device where another thing is closely linked to that particular thing, but is not necessarily a part of it.
Metonymy:
Examples--
Wheels: I got a new set of wheels.
Boots: We put boots on the ground in Iraq.
Vinyl: (and you might not know this one) Bring your vinyls to the party on Friday night.
Gray beard: The phrase “gray beard” refers to an old
man.
Suits: refers to businessmen.
Glasses: refers to spectacles.
White House: The White House announced that the President will address the nation tonight. (hey, Nation too!)
Hollywood: We are going to boycott Hollywood because of its excessive use of sex and violence in television shows.
Pentagon: refers to a few decision makers (military)
Crown: The crown frowns upon gossip at court.
Stiffs: The detective wants to know where the stiffs are (!).
Our text book, Sounds and Sense, states, “Synecdoche and metonymy are so much alike that it is hardly worthwhile to distinguish between them, and the latter term is increasingly coming to be used for both,” and “Such figures are often referred to as dead metaphors” (66). Also consider that many of these have become part of our daily language (like glasses for spectacles) that we don’t even recognize them as figurative language any more.