Triskaidekaphobia

An irrational fear of an ordinary number.

Today is Friday the 13th. Many people fear this day, thinking that the number 13 brings bad luck. The fear of the number 13 is so pervasive that I’ve seen in some buildings, elevators that do not have a button for the 13th floor. That fear is so strong that it has a name: Triskaidekaphobia.