Can any Californian say something about the relative frequency of the various names for this species?
I'd never heard the term "mountain lion" until recently (I think I first encountered it in a story by Annie Proulx) though I've known the word "puma" since the 1970s. Apparently they're also known as "cougar" or "catamount". I probably came across the term "cougar" some time this century, and the term "catamount" a few minutes ago.