A figure of speech in which an implied comparison is made between two unlike things that actually have something in common.

~About.com

“From Stettin in the Baltic to Trieste in the Adriatic an iron curtain has descended across the continent.”

~ Winston Churchill

Part is represented to the whole or the whole represents the part.

>“Take thy face hence.”>>

~Shakespeare, Macbeth

One word or phrase is substituted for another which is closely related or associated with (symbolically linked)

“The pen is mightier than the sword.”