WordWeb Online

1. Using the name of a part for that of the whole or the whole for the part; or the special for the general or the general for the special; or the material for the thing made of it
   "to use 'hand' for 'worker' or 'ten sail' for 'ten ships' or 'steel' for 'sword' is to use a synecdochical figure of speech"
   - synecdochic

See also: figurative, nonliteral, synecdoche

Encyclopedia: Synecdochical