Superstitious (adjective)

1. Believing in or relating to superstition; having or showing superstition.
2. Having or showing an irrational belief in the supernatural or a fear of the unknown.
3. Having or showing an irrational belief that certain actions or events will bring good or bad luck.

Origin:

From the latin word "superstitiosus" meaning relating to excessive fear of the gods or undue reverence for religion.

Examples:

1. She is superstitious and won't walk under ladders.
2. He is superstitious and always carries a lucky charm.
3. Many people are superstitious about the number thirteen.
4. Some athletes are superstitious about their routines before a game.
5. The sailors were superstitious and believed that whistling on a ship would bring bad luck.