a ghost or the spirit of a dead person being seen

ghost

(in stories) an evil spirit

ghost

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

misconception, misbelief

(a spirit of) a dead person appearing to a person still living

spirit of the dead

(an instance of) seeming to see something not actually present

dream, delusion

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

false appearance; false belief

an effect, produced by hot air conditions, causing something (not existing) to become visible (or upside down), especially the appearance of water in the desert

imaginary vision

a ghost

ghost; figment of the imagination

(plural) of phenomenon

something known through senses