Astronomy. the appearance or time when a comet, especially a periodic one, is visible: the 1986 apparition of Halley's comet.
Origin: 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
Synonyms 1. spirit, shade. 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.
1520s, from Anglo-Fr. aparicion, from O.Fr. apparition, used in reference to the Epiphany (revealing of Christ child to the Wise Men), from L.L. apparitionem (nom. apparitio) "an appearance," also "attendants," in classical Latin "service, servants," from pp. stem of apparere "appear" (see