Word for using example to refer to the whole

I was talking with a friend about the word "portmanteau", noticing that it is itself a portmanteau (making it autological), but in particular its meaning seems to have nothing to do with the concept other than being an example of it. If history had run a different course, we might be calling "smog" a blaxploitation.

I'm wondering if there is a word for words in which an example of the concept is used as the concept's name. Would "synecdoche" be appropriate? It doesn't feel quite right.