Orwell, author of 1984, wrote an essay decrying the decay of the English language. Specifically, he lamented that when most people go to write or converse, they rely on stock phrases which they stich together into different patterns, rather than developing original content.
Speculative fiction, broadly, includes the stories that are typically classified as science fiction and fantasy, but if you've written in the genre realm for long, you may have noticed that the terminology employed by libraries and other sources to classify genre fiction is somewhat limited. Maybe we genre writers aren't as "serious" as the "real" authors, but that hasn't stopped us from developing our own terminology to help describe our works. Since I think that many of these terms would be useful for both readers and writers to know, I've sought to describe some of them below.