Synecdoche

synecdoche \sə-ˈnek-də-(ˌ)kē\ noun: a figure of speech by which a part is put for the whole (as wheels for a car), the whole for a part (as body for the trunk of the body), the specific for the general (as hoover for a vacuum cleaner), the general for the specific (as creature for a man), or the name of the material for the thing made (as threads for clothes or ivories for piano keys)

Etymology: Latin, from Greek synekdochē, from syn- with, together with + ekdochē sense, interpretation, from ekdechesthai to receive, understand, from ex from + dechesthai to receive

Today we begin looking at figures of speech. There are so many it would take weeks to cover them all, so I'll whittle them down to about a week's worth of good ones. If there’s a particular figure of speech you want to see covered, let me know.