The part for the whole: I saw a lot of new faces (people) at the last meeting.
The whole for a part: The United States (the US military) is at war.
The material for the object: Paper (a paper bag) or plastic (a plastic bag)?
The general for the specific: Watch out for that bug (any type of insect or spider).
The specific for the general: She's a real Rockefeller (filthy rich person).
The container for its contents: He cleaned his plate (ate all of his meal).
Synecdoche then drops the e and gains an ism to become synecdochism, which can refer to both the use of synecdoche or the belief that something done to part of an object or person affects the whole. In the latter sense, synecdochism describes the thought process behind certain sympathetic magic practices, as when burning a lock of someone's hair is believed to result in harm to that person.
Synecdoche is truly, literally, magical! Unfortunately it is pronounced something like "Schenectady," so not the most mellifluous of words. I guess you can't have it all..though some New Yorkers might beg to differ.