•vision in a dream · phantom, phantasm (something seen but having no physical reality; a figment; an illusion) · phantom, ghost, apparition, spectre (UK), specter (US) (vision of a disembodied soul)
appearance (way of being perceived by others) · apparition, vision (act or instance of becoming perceptible, especially of something transcendent) · phenomenon (something that happens widely or repeatedly)
köken: From spec(iō) (“look at, behold”) + -trum (making it a doublet of speculum). The only attestation in Classical antiquity is in a pair of letters between Cicero and Cassius Longinus which imply that the Epicurean Catius (fl. c. 50s–40s BC) used spectrum as a translation of the Greek philosophical term εἴδωλον (eídōlon, “image”). It may therefore have been coined by Catius as a neologism, although…