The irrational fear of the number 13 has been given a scientific name of 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”).
The superstition surrounding this day may have arisen in the Middle Ages, originating from the story of Jesus’ last supper and crucifixion in which there were 13 individuals present in the Upper Room on the 13th of Nisan Maundy Thursday, the night before his death on Good Friday. While there is evidence of both Friday and the number 13 being considered unlucky, there is no record of the two items being referred to as especially unlucky in conjunction before the 19th century.
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 (2006).