Look:
Because synecdoche is a concept intimately associated with metonymy, not
calling metonymy by name, one could claim that synecdoche is a metonym for
metonymy. By similar standards, because synecdoche is a subset of metonymy,
synecdoche is also a synecdoche of metonymy. The converse is also true.
http://en.wikipedia.org/wiki/Metonymy#Synecdoche
Metonymy - Wikipediaen.wikipedia.org