The word was derived from the Greek words "paraskevi" which means Friday, "dekatreis" which means 13, and "phobia" which refers to fear.
According to Wikipedia, the term paraskevidekatriaphobia was coined in 1911 and first used in mainstream sources in 1953.
Friday the 13th occurs when the thirteenth day of a month falls on a Friday, which superstition holds to be a day of bad luck. In the Gregorian calendar, this day occurs at least once, but at most three times a year. Any month's 13th day will fall on a Friday if the month starts on a Sunday.
Those who are afraid of the number 13, on the other hand, have triskaidekaphobia.
People who believe in superstitions regard the day when the 13th day of the month falls on a Friday as a most unluckiest day.
The incidence of the 13th falling on a Friday may happen up to three times a year.
Bad luck?
Bad things are said to happen on Friday the 13th.
This is why some buildings and hotels do not have a 13th floor. Some streets, on the other hand, do not have a 13th Street.
In the US, the stock market slows down on Friday the 13th, and people postpone travel and spending, resulting in some $900 million lost in earnings, according to the Stress Management Center and Phobia Institute in North Carolina. The Institute believes some 17 million to 21 million people suffer from phobia of Friday the 13th.
Some
people believe that one should avoid seeing a black cat, looking into a
mirror, and throwing salt accidentally, or else bad luck may happen. In
the Middle Ages, people believed that a black cat may in fact be a
witch in disguise.The belief may trace its roots in numerology, where number 13 connotes bad luck.
Since the 14th century, Friday was also considered an unlucky day as it was believed that Jesus Christ was crucified on the cross on a Friday.
Hollywood has capitalized on the Friday the 13th phobia. "Friday the 13th" the movie was released in 1980 and a remake was shown in theaters in 2009.