An apparition is something that appears suddenly and mysteriously, especially something that seems ghostly or supernatural. When people claim to see an apparition, they usually mean they've witnessed a transparent, glowing figure that appears and disappears without explanation, like the ghost of someone who died long ago materializing in an old house.

In A Christmas Carol, Ebenezer Scrooge sees several apparitions: spirits that appear in his bedroom to teach him lessons about his life. Ghost stories often feature apparitions that drift through walls or vanish into thin air.

But apparition doesn't always mean a ghost. It can describe anything that appears suddenly in an almost magical way. You might read about an apparition of light in the sky, or describe how a friend seemed to arrive as if by apparition when you really needed help. The word emphasizes the mysterious, unexpected nature of something's appearance, whether it's actually supernatural or just feels that way.