Astronomy. the appearance or time when a comet, especially a periodic one, is visible: the 1986 apparition of Halley's comet.
Origin of apparition
1400–50;late Middle Englishapparicio(u)n < Anglo-French,Old French < Late Latinappāritiōn- (stem of appāritiō, as calque of Greekepipháneiaepiphany), equivalent to Latinappārit(us) (past participle of appārēre; see appear) + -iōn--ion
Related formsap·pa·ri·tion·al, adjectivenon·ap·pa·ri·tion·al, adjective
1. Apparition,phantasm,phantom are terms for a supernatural appearance. An apparition of a person or thing is an immaterial appearance that seems real, and is generally sudden or startling in its manifestation: an apparition of a headless horseman. Both phantom and phantasm denote an illusory appearance, as in a dream; the former may be pleasant, while the latter is usually frightening: a phantom of loveliness; a monstrous phantasm.
c.1500, "unclosing" (of Heaven), from Anglo-French aparicion, Old French apparition, aparoison (15c.), used in reference to the Epiphany (revealing of Christ child to the Wise Men), from Late Latin apparitionem (nominative apparitio) "an appearance," also "attendants," in classical Latin "service, servants," noun of action from past participle stem of apparere "appear" (see appear). Meaning "ghost" first recorded c.1600; the shade of sense differentiation between appearance and apparition is that the latter tends to be unexpected or startling.