Schwarz
Was verborgen ist — das Unbekannte, Unbewusste, was Sie noch nicht ans Licht gelassen haben.
Black in a dream is the dictionary's image for the not-yet-known. A black room is a part of you that you have not yet entered. A black object handed to you is information you are being asked to take in even though it is hard to see clearly yet.
Black is rarely the negative image waking culture treats it as. In dreams, it is depth — the soil from which things grow before they are visible.
Where you often see it. A black room you are entering. A black object handed to you. Black water at the edge of vision. The dream is asking you to take in something that is not yet illuminated and to keep the lights low while you do.
What it is not. Black in the dictionary is not death and it is not evil. It is what has not yet been brought into language. The reading is steady; do not let cultural overlays decide it for you.
Related in the dictionary. Read alongside white (clarity), grey (ambiguity), darkness (the same field, in landscape form), and night-time contexts of the symbol you actually saw.