the act, state, of deluding or being deluded; a false opinion or belief, especially one that may be a symptom of madness

misconception, misbelief

something which one seems to see or experience during sleep

illusion, vision

wild or extravagant creative thought or mental pictures

imagination, dream

something invented or imagined

creation in one's mind

a feeling of desire, trust, confidence; to expect and desire something that is possible

longing; dream

(the seeing of) something that does not really exist; a false or impossible idea

false appearance; false belief

a ghost

ghost; figment of the imagination

to think (about something)

think about seriously