Somewhere, I read an article to the effect that the term "fundamentalist" was not applicable to Islam because the history of disputatious biblical exegesis to which it refers does not exist in Islam. I have no idea if that claim makes sense.
However, like "evangelical" - and to an even greater extent - it has in common parlance become a catch-all derogatory term for religious wingnuts. And I don't think it's worth the bother to try to salvage the original meaning of the word (at least not outside scholarly discourse).
- Jake Ceterum censeo Chicago esse delendam