apparition

Etymology

From Middle French apparition, from Latin apparitio, from appareo.

noun

1. An act of becoming visible; appearance; visibility.
2. The thing appearing; a visible object; a form.
3. An unexpected, wonderful, or preternatural appearance; especially something such as a ghost or phantom.
   The attic is haunted by the ghostly apparition of a young girl who died there.
   The apparition wobbled in front of Arthur's eyes, though the truth of the matter is probably that Arthur's eyes were wobbling in front of the apparition. 1982, Douglas Adams, Life, the Universe and Everything, page 24
4. (astronomy) The first appearance of a star or other luminary after having been invisible or obscured; opposed to occultation.
5. (astronomy) A period of consecutive days or nights when a particular celestial body may be observed, beginning with the heliacal rising of the body and ending with its heliacal setting.