a figure of speech in which a part is used for a whole, an individual for a class, a material for a thing, or the reverse of any of these (Ex.: bread for food, the army for a soldier, or copper for a penny)
A figure of speech in which a part is used for the whole (as hand for sailor), the whole for a part (as the law for police officer), the specific for the general (as cutthroat for assassin), the general for the specific (as thief for pickpocket), or the material for the thing made from it (as steel for sword).
Origin: Middle English synodoches, from Medieval Latin synodoche, alteration of Latin synecdochē, from Greek sunekdokhē, from sunekdekhesthai, to take on a share of : sun-, syn- + ekdekhesthai, to understand (ek-, out of; see eghs in Indo-European roots + dekhesthai, to take; see dek- in Indo-European roots).