The term "sci-fi" was used by Robert A. Heinlein in private correspondence as early as 1949 and was publicly adopted as an alternate form of "science fiction" by Forrest ("Forry") J. Ackerman by 1954. Ackerman was a film review writer who became the editor of Famous Monsters of Filmland magazine, which celebrated the monster/SF movies that were frowned upon by many hardcore science fiction fans as being too poor in quality to be taken seriously, and definitely not to be confused with "real" science fiction.
In the late 1960s, a new movement of science fiction writers, the "New Wave", arose. It tended to reject science fiction's pulpy background and to scorn the term "sci-fi" as being associated with bad monster movies. Even the term "science fiction" was seen by some in the New Wave as too limiting, and "speculative fiction" was introduced as an alternative. Some advocated the use of the initials "SF", as they could be taken to refer to either "science fiction" or "speculative fiction". Not everyone agreed with this new nomenclature, however, and while the term "sci-fi" continued to be widely used, and pronounced "sigh-fie", the pronunciation "skiffy" began to appear among science fiction insiders in the late 1970s.
One of the first well-documented uses of the term "skiffy" was in the name of a science fiction and fantasy fan club at the University of Chicago, which was formed during the 1980s, and lasted until it was disbanded in 2003. Skiffy is still the name of the science fiction and skiffy club at the College of William and Mary,, as well as shorthand (not always affectionate) for the American cable channel, Sci Fi.
By the late 1990s, the term "skiffy" was well-enough accepted that Mike Resnick and Patrick Nielsen Hayden released a book called Alternate Skiffy, an anthology featuring stories about what might have happened if the lives of various well-known science fiction writers had turned out differently.
Skiffy is a supplier of small plastic and metal parts. The founder of the company, Johan Putzfeld, used his little dog's name Skiffy as a brand name.