Synecdoche

A synecdoche (/sɪˈnɛkdəkiː/, si-NEK-də-kee; from Greek συνεκδοχή, synekdoche, lit. "simultaneous understanding") is a figure of speech in which a term for a part of something refers to the whole of something or vice versa. A synecdoche is a class of metonymy, often by means of either mentioning a part for the whole or conversely the whole for one of its parts. Examples from common English expressions include "bread and butter" (for "livelihood"), "suits" (for "businesspeople"), and "boots" (for "soldiers"). Synecdoche also appears in the use of government buildings to refer to their occupant or agency, as "No. 10" for the British Prime Minister or "The Pentagon" for the United States Department of Defense.