Down in meta-words, I posted a list containing word "chatelaine". This I recognized
as French for a lady in charge of a chateau or similar large important dwelling place,
as far at responsibility for security, supervision of servants, etc. So imagine my
surprise at seeing it defined as a key ring, on which the keys to the estate might
be kept. It is obviously a metaphor, but the reverse of the usual kind. Yet dictionary
defintion of "synecdoche" = name of part = whole, says "or reverse".
So is synecdoche the right word in this case? Or is there a better word for it?

Please comment.