(n.) An invention; a fiction; something feigned or imagined.

apparition brainchild bubble canard chimera concoction creation daydream delirium dream eidolon extravaganza fable fabrication fancy fantasque fantasy fiction forgery hallucination idle fancy illusion imagery imagination imagining insubstantial image invention maggot make-believe myth nightmare phantasm phantom romance sick fancy thick-coming fancies trip vapor vision whim whimsy wildest dreams