apparition

noun

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

1. An act of becoming visible; appearance; visibility.

   “the sudden apparition of the Spaniards”

   “The apparition of Lawyer Clippurse occasioned much speculation in that portion of the world.”

2. The thing appearing; a visible object; a form.

   “[…] which apparition, it seems, was you.”

3. An unexpected, wonderful, or preternatural appearance; especially, one by a ghost, phantom, or suchlike; the entity itself.

   “The region's economy is buoyed by tourism driven by past apparitions of the Virgin Mary.”

   “The attic is said to be haunted by the ghostly apparition of a young girl who died there.”

4. The first appearance of a star or other luminary after having been invisible or obscured; opposed to occultation.
5. 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.