This article is from the rec.arts.sf.written FAQ, by Evelyn C. Leeper evelynleeper@geocities.com with numerous contributions by others.
This subject has been hashed out endlessly, and if you really want to
see all the definitions proposed (or at least a very substantial
subset), they have been collected by Neyir Cenk Gokce [gokce@panix.com]
at http://www.panix.com/~gokce/sf_defn.html, or Beth and Richard
Treitel's page at http://web.treitel.org/sf/sf.html. The only
definition that seems to work is Damon Knight's: "Science Fiction
is what we point at when we say it." Unless you have something really
new and amazing, don't start this topic. [Provided by Evelyn Leeper
[evelynleeper@geocities.com] and Taki Kogoma [quirk@vesta.unm.edu].]
[If you *think* you have something new and amazing, try applying it
to the following cases:
alternate history novels
novels set on another planet with no contact with Earth and
no unknown technology (e.g., HELLO SUMMER, GOODBYE
by Michael Coney, and possibly AGAINST A DARK BACKGROUND
by Iain M. Banks)
SWORDSPOINT by Ellen Kushner]
As for the origin of the term itself, according to Sam Moskowitz in
EXPLORERS OF THE INFINITE: SHAPERS OF SCIENCE FICTION (page 240):
"The first issue of SCIENCE WONDER STORIES was dated June
 
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