@anon252973: I've worked for a newspaper for nearly 20 years, and as I understand the slander definitions, a person has to make a more specific allegation for a statement to meet the criteria of slander.
Calling someone a "bimbo" (to use a less pejorative word than Limbaugh did) is calling someone an ugly name. He didn't say he "knew" she was a bimbo because he knew she slept around, or whatever. He didn't cite a specific instance of Ms. Fluke being promiscuous, and I doubt anyone listening felt he had some specific knowledge which made it anything other than him calling her an ugly name. He was just (to use a good Bill O'Reilly word) "bloviating," and I think people understood that, even if some may have said under their breath, "Yeah, she probably is a bimbo." That still doesn't rise to the level of slander, and certainly, she hasn't suffered any harm from it. On the contrary, she has garnered a great deal of sympathy and support.
So even though it was a rude, crude and socially unacceptable thing to say, and certainly not something anyone with any home training should say about someone he doesn't know, it wasn't slander.