YEREVAN, JANUARY 13, ARMENPRESS. Friday the 13th, considered by many to be the unluckiest day of the year according to Western superstition, is here again.

The fear of the number 13 has been given a scientific name: "triskaidekaphobia"; and on analogy to this the fear of Friday the 13th is called paraskevidekatriaphobia, from the Greek words Paraskeví (Παρασκευή, meaning "Friday"), and dekatreís (δεκατρείς, meaning "thirteen"). In medicine this phenomena is viewed as a phobia.

It is possible that the publication in 1907 of Thomas W. Lawson's popular novel Friday, the Thirteenth, contributed to disseminating the superstition. In the novel, an unscrupulous broker takes advantage of the superstition to create a Wall Street panic on a Friday the 13th.

A suggested origin of the superstition—Friday, 13 October 1307, the date Philip IV of France arrested hundreds of the Knights Templar—may not have been formulated until the 20th century. It is mentioned in the 1955 Maurice Druon historical novel The Iron King (Le Roi de fer), John J. Robinson's 1989 work Born in Blood: The Lost Secrets of Freemasonry, Dan Brown's 2003 novel The Da Vinci Code and Steve Berry's The Templar Legacy.

According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17 to 21 million people in the United States are affected by a fear of this day, making it the most feared day and date in history. Some people are so paralyzed by fear that they avoid their normal routines in doing business, taking flights or even getting out of bed. "It's been estimated that [US]$800 or $900 million is lost in business on this day". Despite this, representatives for both Delta Air Lines and now-defunct Continental Airlines have stated that their airlines do not suffer from any noticeable drop in travel on those Fridays.

In 2017, there happen to be two Friday the 13ths – January 13 and October 13.

Information – Wikipedia and other sources