A dreamsign is a place, person, object or event that keeps reocurring in your dreams which can be used to tip you off or clue you into the fact that you may be dreaming.

You know right now that you only see this person in dreams, yet in the dream you lose this sense of reasoning and carry on as if it were real. By training your mind to remember that this person is an indication of you dreaming, you will be able to become lucid when he appears next time.