Rhetorical device: Synecdoche

definition

Synecdoche

(syn·ec·do·che)

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).

(American heritage dictionary) 

Why You Might use it

You could use this device to generalize or specify a person or object.

Examples

Example#1:Mr. Murray presented his slideshow using his Macbook*

                      *(laptop computer)

Example#2:Jon tossed the pigskin* 

                      *(pigskin is a part of a football)

Example from the media: Take Thy face hence (Act V, Scene III. Macbeth, Shakespeare)

In REAL english:                (take your face* away from me)

                      *(Face refferes to the entire person (the servent))