Metonymy

• These noises of boots → military Coup d'etat, because the soldiers are usually fitted boots and make noise while gathering and while walking to the step.

• the Garonne → people who live close to the the Garonne (“the Garonne invaded the Stade de France”).

Synecdoque

The direction is extended here to a unit vaster including/understanding what is indicated by the word, or on the contrary restricted with an element contained in him (synecdoque of the whole or part), which it is about a space inclusion or simply logic. Examples:

• wheels → cars (“the city is invaded wheels”)
• biped → man (“I saw a biped getting into the bus”)

Difference between the two figures

If one observes the examples above, one notices that…

• the soldiers can not make noise very well, to move out of tanks, and not to carry boots. In the same way, the Garonne did not leave its bed. The metonymy has a fantastic side.
• on the other hand, the wheels are indeed in the streets and that which is gotten into the bus was well a biped. The synecdoque one is more realistic.

Complementary remark

It is necessary to make the difference between the synecdoques métonymies and the lexiconized and those which are new, poetic, rhetorics or humorous.

In the first case, there is no more really of figure. Thus, the word office evolved/moved by metonymy, of the part of bore-hole to the piece of furniture which it covered, then at piece-rates containing this piece of furniture (métonymie-synecdoque). Today, no one does not think of the frieze when he hears of an office.