Friggatriskaidekaphobia (try saying that ten times fast) is the fear of Friday the 13th. Approximately 17-21 million Americans suffer a fear of Friday the 13th, according to the Stress Management Center and Phobia Institute.
The number ‘13’ has been considered an unlucky number for centuries, and Friday has been considered the week’s unluckiest day. In numerology, 12 is considered the number of completeness: the 12 signs of the zodiac, 12 hours of the clock, the 12 Apostles, and so on. The number 13 is considered a violation, going beyond completeness. This fear carries over into modern day suspicions, with many building floors skipping from the 12th to the 14th floor, the number 13 being skipped when assigning hotel room numbers, and athletes avoiding having the number on their jerseys.
Friday has been considered less unlucky than the number ‘13’ (likely because it occurs every seven days), but it is still thought of as unlucky in a number of circles. Jesus was crucified on a Friday, the stock market crash of 1929 happened on Black Friday, some people consider Friday to be the witches’ day.