Apparition dream meaning is explained below using 7 different sources. Each interpretation is shown with its source.

Interpretation 1 — Gustavus Hindman Miller

Take unusual care of all depending upon you. Calamity awaits you and yours. Both property and life are in danger. Young people should be decidedly upright in their communications with the opposite sex. Character is likely to be rated at a discount.
Source: Ten Thousand Dream Interpretation Author: Gustavus Hindman Miller

Interpretation 2 — Internet Archive - Anonymous

No harm is foretold by a dream of ghosts or other Apparitions, unless their presence or sudden appearance frightens you or makes you ill. In that case, you must expect financial difficulties, perhaps ill-health
Source: Mystic Dream Book Author: Internet Archive - Anonymous

Interpretation 3 — Pagan - Anonymous

Seeing an apparition in a dream is a portent of serious illness.

If the apparition is of someone you know, you will probably want to contact the person soon to ensure s/he is alright.

Source: Tryskelion Dream Interpretation Author: Pagan - Anonymous

Interpretation 4 — DreamForth

To see an apparition in your dream symbolizes your inner essence and personality. It may also represent your ethics and morals.
Source: Dream Symbols and Analysis Author: DreamForth

Interpretation 5 — Stearn Robinson - Tom Corbett

The portent is of good news unless the apparition frightened you or made you feel ill, in which case a medical checkup is
Source: The Complete Guide to Interpreting Your Dreams Author: Stearn Robinson - Tom Corbett

Interpretation 6 — Silvana Amar

Purification of negativity is needed immediately. Begin with the inside of yourself and work to the outside. 
Source: The Bedside Dream Dictionary Author: Silvana Amar

Interpretation 7 — Joan Seaman - Tom Philbin

Someone or something one is afraid of.
Source: New American Dream Dictionary Author: Joan Seaman - Tom Philbin