Apparitions dream meaning is explained below using 2 different sources. Each interpretation is shown with its source.

Interpretation 1 — Stephen Girard

To dream you see a ghost, hobgoblin, spectre, and such kind of things, is of a very unfortunate nature; it denotes vexation and disappointment; if you are in love, it is a certain sign of your not being beloved in return, depend upon it, someone is about to deceive you, and that you are in habits of friendship with one who is your most inveterate enemv. To dream you see an apparition, or spirit, clothed in white, signifies deceit and temptation to sin. 
Source: The Mystic Dream Book Author: Stephen Girard

Interpretation 2 — Tony Crisp

See ghost.
Source: A Guide to Dreams and Sleep Experiences Author: Tony Crisp