Synecdoche is a way of speaking where you name a part of something but mean the whole thing, or name the whole but mean one part. 'We need more hands on the farm' — you do not want hands, you want people. 'Nice wheels!' — the wheels stand for the whole car. 'England lost to Brazil' — two whole countries stand for eleven players each. It is not a mistake; it is one of the ordinary machines of everyday language, and speakers use it without noticing. The word itself is technical and literary: you meet it in English classes, in books about writing and rhetoric, and almost never in conversation. Say it roughly si-NEK-duh-kee — four syllables, and the 'ch' is a k sound, which surprises everyone. The adjective is 'synecdochic' or 'synecdochical', both rare. Teachers often treat it as a close relative of metonymy, where you name something by a thing connected to it ('the White House said today'). The tidy line between the two is that synecdoche uses a part-and-whole relationship while metonymy uses any close connection — though in practice scholars argue about which examples belong where, and many writers just say metonymy for both.

提喻（修辭格：以部分代全體，或以全體代部分）