SF

According to Neil Gaiman Science Fiction should be call Speculative Fiction.
After listening to the TED Radio Hour 'Spoken and Unspoken' episode I think perhaps Subjunctive Fiction fits better and (with Phuc Tran's talk as background context) evokes more of the power of the genre. SF can express ideas that could not be explored at all without the background fictional conceits used.

Though that also probably sounds too professorial for ordinary use.