For the myth, it would be considered 7 years of bad luck.
On another note: Black cats are not a sign of bad luck, that is just an old myth. Cats are black because of there dna/genes NOT because they are bad luck, because they are NOT.
They don't, its just psychological. you think your gonna have bad luck so when something that would normally go wrong goes wrong, you blame it on the cat.
In ancient history, especially in the Fertile Crescent, there were opposing beliefs about the black cat, and how you viewed the animal depended upon your culture and religion. Ancient Egyptians...
100% Myth. I own one and have had her for (5?) years and she has crossed my path many times. If you wish to own one but are afraid of bad luck go get one and try it out! The only thing that could...