Чёрная кошка
Знание, удерживаемое в темноте — народное везение, смешанное с интуицией, которую вы ещё не присвоили.
A black cat in a dream is the dictionary's image of knowledge that lives in the dark — the kind of intuition you have but have not yet acknowledged as yours. The folk-luck reading varies by culture; the dream tends to use whichever your culture gave you and then quietly complicate it.
The more important reading is internal: the black cat is usually a piece of you that knows something you have been refusing to admit you know.
Where you often see it. A black cat crossing a path. A black cat sitting on a step at twilight. The dream uses the black cat for knowledge held in the dark — folk-luck mixed with intuition you have not yet claimed.
What it is not. A black cat is not bad luck in the dictionary's register. That overlay is cultural; the dream reads it as quiet, discerning presence.
Related in the dictionary. Read cat-black with cat, the colour black, and any scene of quietly-watching wisdom.