If your sister gets a flat tire every single time you ride in her car, she may have good reason to accuse you of being a jinx, or a bringer of bad luck.
When your bad luck makes you think there's a jinx on you, you believe that you're cursed. A bad omen — like a black cat — can be called a jinx, or the resulting bad fortune itself might be referred to that way. Jinx is also a verb, meaning "to subject to bad luck." In the 17th century the word was jyng, which also meant a bird called a "wryneck," used in witchcraft.