synecdoche (n.) Look up synecdoche at Dictionary.com
late 14c., "part for whole or vice versa," from Medieval Latin synodoche, from Late Latin synecdoche, from Greek synekdokhe, literally "a receiving together or jointly," from synekdekhesthai "supply a thought or word, take with something else," from syn- "with" (see syn-) + ek "out" (see ex-) + dekhesthai "to receive," related to dokein "seem good" (see decent). Figure in which an attribute or adjunct is substituted for the thing meant ("head" for "cattle," etc.).