Triskaidekaphobia (// TRIS-kye-DEK-ə-FOH-bee-ə, /-/ TRIS-kə-; from Ancient Greek τρεισκαίδεκα (treiskaídeka) 'thirteen', and Ancient Greek φόβος (phóbos) 'fear') is fear or avoidance of the number 13. It is also a reason for the fear of Friday the 13th, called paraskevidekatriaphobia (from Greek Παρασκευή (Paraskevi) 'Friday', Greek δεκατρείς (dekatreís) 'thirteen', and Ancient Greek φόβος (phóbos) 'fear') or friggatriskaidekaphobia (from Old Norse Frigg 'Frigg', Ancient Greek τρεισκαίδεκα (treiskaídeka) 'thirteen', and Ancient Greek φόβος (phóbos) 'fear').
The term was used as early as in 1910 by Isador Coriat in Abnormal Psychology.
The supposed unlucky nature of the number 13 has several theories of origin. Although several authors claim it is an older belief, no such evidence has been documented so far. In fact, the earliest attestation of 13 being unlucky is first found after the Middle Ages in Europe.
Tarot card games have been attested since at least around 1450 with the Visconti-Sforza Tarot. One of the trump cards in tarot represents death and is the card number 13 in several variants.
In 1781, Antoine Court de Gébelin writes this in a French book involving Tarot of Marseilles:
Le no. XIII. représente la Mort [...] Il n'est pas étonnant qu'elle soit placée sous ce numéro; le nombre treize fut toujours regarde comme malheureux.
Number XIII represents Death [...] It is not astonishing that it is placed under this number; the number thirteen was always looked upon as unlucky.
In 1784, Johann Gottlob Immanuel Breitkopf writes a German book on the origins of playing cards, cites Gébelin, and reaffirms that the tarot card number 13 is death and misfortune ("Der Tod, Unglück").
Since at least 1774, a superstition of "thirteen at a table" has been documented: if 13 people sit at a table, then one of them must die within a year. The origin of the superstition is unclear and various theories of its source have been presented over the years.
In 1774, Johann August Ephraim Götze speculated:
Da ich aus der Erfahrung weis, daß der Aberglaube nichts liebers, als Religionssachen, zu seinen Beweisen macht; so glaube ich bey nahe nicht zu irren, wenn ich den Ursprung des Gegenwärtigen mit der Zahl XIII, von der Stelle des Evangelii herleite, wo der Heiland, bey der Ostermahlzeit, mit zwölf Jüngern zu Tische saß.
Since I know from experience that superstition loves nothing better than religious matters as its proofs, I believe I'm almost unmistaken when I derive the origin of the matter of the number XIII from the passage of the Gospel where the Savior sat at table with twelve disciples at the Easter meal.
From the 1890s, a number of English-language sources reiterated the idea that at the Last Supper, Judas, the disciple who betrayed Jesus, was the 13th to sit at the table. The Bible says nothing about the order in which the Apostles sat, but there were thirteen people at the table.
In 1968, Douglas Hill in Magic and Superstitions recounts a Norse myth about 12 gods having a dinner party in Valhalla. The trickster god Loki, who was not invited, arrived as the 13th guest, and arranged for Höðr to shoot Balder with a mistletoe-tipped arrow. This story was also echoed in Holiday folklore, phobias, and fun by folklore historian Donald Dossey, citing Hill. However, in the Prose Edda by Snorri Sturluson, the story about Loki and Balder does not emphasize that there are 12 gods, nor does it talk about a dinner party or the number 13.
In some regions, 13 is or has been considered a lucky number. For example, prior to the First World War, 13 was considered to be a lucky number in France, even being featured on postcards and charms. In more modern times, 13 is lucky in Italy except in some contexts, such as sitting at the dinner table. In Cantonese-speaking areas, including Hong Kong and Macau, the number 13 is considered lucky because it sounds similar to the Cantonese words meaning "sure to live" (as opposed to the unlucky number 14 which in Cantonese sounds like the words meaning "sure to die"). Colgate University was started by 13 men with $13 and 13 prayers, so 13 is considered a lucky number. Friday the 13th is the luckiest day at Colgate.
A number of sportspeople are known for wearing the number 13 jersey and performing successfully. On November 23, 2003, the Miami Dolphins retired the number 13 for Dan Marino, who played quarterback for the Dolphins from 1983 to 1999. Kurt Warner, St. Louis Rams quarterback (NFL MVP, 1999 & 2001, and Super Bowl XXXIV MVP) also wore number 13. Wilt Chamberlain, 13-time NBA All-Star, has had his No. 13 Jersey retired by the NBA's Golden State Warriors, Philadelphia 76ers; Los Angeles Lakers, Harlem Globetrotters, and Kansas University Jayhawks, all of which he played for. In 1966, the Portugal national football team achieved their best-ever result at the World Cup final tournaments by finishing third, thanks to a Mozambican-born striker, Eusebio, who has scored nine goals at World Cup – four of them in a 5-3 quarterfinal win over North Korea – and won the Golden Boot award as the tournament's top scorer while wearing the number 13. In the 1954 and 1974 World Cup finals, Germany's Max Morlock and Gerd Müller, respectively, played and scored in the final, wearing the number 13. More recent footballers playing successfully despite wearing number 13, include Michael Ballack, Alessandro Nesta, and Rafinha. Among other sportspeople who have chosen 13 as their number, are Venezuelans Dave Concepción, Omar Vizquel, Oswaldo Guillén and Pastor Maldonado due to the number being considered lucky in Venezuelan culture. Swedish-born hockey player Mats Sundin, who played 14 of his 18 NHL seasons for the Toronto Maple Leafs, setting team records for goals and points, had his number 13 retired by the team on 15 October 2016.
Outside of the sporting industry, 13 is used as a lucky number by other individuals, including Taylor Swift who has made prominent use of the number 13 throughout her career.