Cormac McCarthy's The Road is set during a nuclear winter. Two survivors walk south, breathing toxic air, seeking out the continent's last canned food while ducking bands of flesh-eaters.

Describe it as "post-apocalyptic," as most critics did, or as a masterpiece of dystopian literature. Just don't call McCarthy's novel "science fiction."

Even when clearly appropriate, film studios and publishers avoid the phrase "science fiction." So do the novelists, film directors and editors in their employ. McCarthy's book, which is about to become a blockbuster – Oprah Winfrey will tout it on an upcoming TV show as part of her book club – is just another example of how the powers that be dodge the term, especially when it applies to "serious" fiction or cinema.

You won't find the words "science fiction" in Random House's bio of Arthur C. Clarke Award-winning author China Miéville. Instead, he's called the "edgiest mythmaker of the day." Michel Gondry's The Science of Sleep? It's classified as comedy, drama, romance and fantasy, but not sci-fi, at Amazon.com.

Even Battlestar Galactica, the flagship show of (hello!) the Sci Fi Channel, keeps a distance. "It's fleshed-out reality," explains executive producer Ronald D. Moore in the sci-fi mag SFX. "It's not in the science-fiction genre."

The nose-thumbing is nothing new. In the '50s, Robert Heinlein dismissed the term, opting for "speculative fiction." (What fiction isn't?)

But today, one might imagine that the term could gain traction. Our lives are entangled with everyday gadgetry Heinlein could only have dreamed of. The impact of science on culture – climate change, stem-cell research, the internet – is the subject of continuous debate. Writers including McCarthy and Margaret Atwood (another despiser of the term "sci-fi") and filmmakers like Gondry, Richard Linklater and Darren Aronofsky have explored the terrain of traditional sci-fi.

Plus, the term itself – isolated from its pulpy origins, the fanboy confabs and the endless sniping over its definition – remains an evocative one. Science fiction: stories that engage with science.

Chris Barsanti, a critic who dared to reference The Road in terms of sci-fi literature, said the phrase "science fiction" summons images of "space battles, aliens, mad scientists, time travel and the like ... fantasy with testosterone." So publishers, wary of putting their book into an "artistic ghetto," twist themselves into knots to avoid using the label.

In the face of its shrinking reputation, some institutions are attempting to legitimize science fiction. In 2004, Microsoft co-founder Paul Allen opened Seattle's Science Fiction Museum and Hall of Fame, and The Alfred P. Sloan Foundation gives grants to those who incorporate scientific subject matter into their fictional works.

The University of Kansas and the University of California at Riverside have substantial sci-fi collections. And the University of Liverpool offers a master's degree in science-fiction studies and publishes the scholarly journal Foundation.

"There's been a vast increase in the popularity of science fiction: big special effects movies, TV, games," says Andy Sawyer, head of Liverpool's sci-fi department. "But you rarely see it in the best-seller charts, unless it's dropped the name 'science fiction.'"