Kes is spot on about the term steampunk originally being used as a type of divergent reality based on a different path of advancement from Victorian era steam technology. However, the term, as far as I understand it, has become an acceptable way to describe any world reliant on a technological system which is an equivalent alternative to our own.

Also, Bastian, I'm not sure what your professors have been telling you, but I've never heard fantasy described as a sub-genre of science fiction. I stand by my previous statement of science fiction being a sub-genre of fantasy or, as both Omecle and Kes have acknowledge, a sub-genre of speculative fiction. I'm sorry, chief, you're the one bass ackwards in this case. Also, I'm also a literature major (with a focus in creative writing), so it seems that we're at a stalemate in that regard.

I just fail to see how science fiction (defined as "a form of fiction that draws imaginatively on scientific knowledge and speculation in its plot, setting, theme, etc.") could possibly be a sub-genre of fantasy (defined as "an imaginative or fanciful work, esp. one dealing with supernatural or unnatural events or characters"). It seems that science fiction carries the definition with more specific requirements. By these definitions, fantasy is clearly the broader genre, and it's impossible for a sub-genre to be broader in scope than its parent genre.