According to dictionary.com a superstition is:
1. a belief or notion, not based on reason or knowledge, in or of the ominous significance of a particular thing, circumstance, occurrence, proceeding, or the like.
2. a system or collection of such beliefs.
3. a custom or act based on such a belief.
4. irrational fear of what is unknown or mysterious, esp. in connection with religion.
5. any blindly accepted belief or notion.