To have any desire, idea, or plan that is unlikely to be realized; to imagine visionary projects or schemes; to have an idle fancy or a pipe dream; to daydream.
To fantasize (about).
To imagine; to conceive mentally.
That which comes from one's imagination.
A fantastical design.
The drug gamma-hydroxybutyric acid.
The literary genre generally dealing with themes of magic and the supernatural, imaginary worlds and creatures, etc.