"According to the American Psychiatric Association, a phobia is an uncontrollable, irrational, and persistent fear of a specific object, situation, or activity." [1]
List of the top ten phobias:
Triskadekaphobia is a superstitious fear of the number 13. The most popular cultural expression of this fear is the conception that Fridays occurring on the 13th day of a month (Friday the 13th) are considered bad luck. Of interest is that mathematically, Friday is the most common weekday in the Gregorian calendar on which the 13th can occur.
Since medieval times, association of bad luck with the number has been associated to the fact 13 people attended the Last Supper of Jesus.