Jinx (noun)

1. A person or thing that brings bad luck.
2. An event or situation that causes a string of bad luck.

Origin:

Late 19th century: of uncertain origin; possibly from jynx, the latin name for the wryneck, a bird whose call was thought to bring bad luck.

Examples:

1. He was convinced that he was a jinx and that bad things always happened when he was around.
2. The team had a jinx on them and they couldn't seem to win a game.
3. She was afraid of breaking the jinx, so she didn't want to talk about the upcoming exam.
4. The superstitious player believed that the opposing team's star player was a jinx.
5. The manager thought that the plant was a jinx and decided to close it.