Oxford English Dictionary
Etymology: < Old French fantasie (French fantaisie ), (= Provencal fantazia , Spanish, Portuguese fantasía , Italian fantasia ), < Latin phantasia , < Greek ϕαντασία lit. ‘a making visible’, < ϕαντάζειν to make visible, < ϕαίνειν to show.
The senses of ϕαντασία . . . are: 1. appearance, in late Greek especially spectral apparition, phantom (so Latin phantasia . . .); 2. the mental process or faculty of sensuous perception; 3. the faculty of imagination. These senses passed through Old French into English, together with others (as delusive fancy, false or unfounded notion, caprice, etc.) . . . . The shortened form "fancy" . . . had in the time of Shakespeare become more or less differentiated in sense. . . .
2.a. A spectral apparition, phantom; an illusory appearance. Obs.
3.a. Delusive imagination, hallucination; the fact or habit of deluding oneself by imaginary perceptions or reminiscences. ? Obs.
b. A day-dream arising from conscious or unconscious wishes or attitudes.
4. a. Imagination; the process or the faculty of forming mental representations of things not actually present. (Cf. "fancy") . . . Extravagant or visionary fancy.
c. A product of imagination, fiction, figment.
f. A genre of literary compositions: F. Brown, Angels and Spaceships 9 "Fantasy deals with things that are not and cannot be. Science fiction deals with things that can be, that some day may be."
5.a. A supposition resting on no solid grounds; a whimsical or visionary notion or speculation.
email from UHCL LITR BA Brittany Fletcher:
. . . We go to book stores and libraries and the Fantasy section is mixed in with Sci-fi because they are so closely related today, whereas that was not always the case.
Harry Potter and Twilight are unfortunately the biggies of today! Ha!
But some other known popular selections may be The Hunger Games, The Sookie Stackhouse series (the True Blood TV show), Eragon series, the Percy Jackson series, these are the more young adult fantasy series.
Perhaps Stephen King's Gunslinger series in some would argue.
The question could be raised as to why Fantasy mostly comes in form of series today? I think this genre would make for some great classroom discussion on how the definition has become blurry . . . .
Dr. White adds:
Fantasy has an Anglophilic sheen: adventures seem mostly to occur in some Medieval / Renaissance European settings.
+ Christian fantasy (as in C.S. Lewis's Lion, Witch, Wardrobe series) places its Anglophilia in the Victorian-Edwardian era of the late 1800s-early 1900s.
Harry Potter is highly Anglo--plus the name of Perceval "Percy" Jackson relocates fantasy to a past mixed from European chivalry and Greek mythology.