'fanciful thinking' is a correct and usable phrase in written English.
You can use it to describe any kind of imaginative, unrealistic idea or notion. For example: "Mary's claim that she saw a unicorn in the park was just an example of her fanciful thinking."
It is not fanciful thinking.
At a briefing, Dana Perino, Mr. Bush's press secretary, called Mr. Ahmadinejad's remarks "fanciful thinking".
"Sure, they'd all like to go to the NBA," Blake says, "and nobody wants to go to school". The rapid success of Minnesota Timberwolves forward Kevin Garnett, a '95 high school grad who just signed the richest contract in sports history -- six years, $125 million -- only encourages fanciful thinking.
As it turned out, this wasn't entirely fanciful thinking on my part.
The Enlightenment was a period in history when fanciful thinking gave way to a more rational understanding of cause and effect.
The brush-off received by Digiulio should end any fanciful thinking that somehow a news organization can cover the news with a conflicted boss.
The idea that people who are deterred from visiting a library by the cost of bus fare will soon be awash in Kindles and iPads is more fanciful than thinking that Santa Claus can save a library.
That suspicion, first raised when Diana accuses her husband of having murdered their mentally disturbed son, becomes an obsession with David when she initiates his teenage daughter into her fanciful way of thinking.
When Carrière and Bunuel had the idea of making The Milky Way (1967), an episodic and often obscure film on Catholic heresies, they soon dismissed it, thinking it too fanciful.
They started thinking about a fanciful application: using DNA to apocalypse-proof human culture.
It is a mode of thinking that is not just fanciful imagining but is directed to objects whose reality can be determined.
