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' and from 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.
Origins 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.
Playing cards
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 numbered 13 in several variants. In 1781, Antoine Court de Gébelin writes of this card's presence in the Tarot of Marseilles that the number thirteen was "toujours regarde comme malheureux" ("always considered as unlucky"). In 1784, Johann Gottlob Immanuel Breitkopf cites Gébelin, and reaffirms that the tarot card number 13 is death and misfortune ("Der Tod, Unglück").
13 at a table 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 certainly 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 Superstition 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.
Events related to "unlucky" 13
On Friday, October 13, 1307, the arrest of the Knights Templar was ordered by Philip IV of France. While the number 13 was considered unlucky, Friday the 13th was not considered unlucky at the time. The incorrect idea that their arrest was related to the phobias surrounding Friday the 13th was invented early in the 21st century and popularized by the novel The Da Vinci Code. In 1881, an influential group of New Yorkers, led by US Civil War veteran Captain William Fowler, came together to put an end to this and other superstitions. They formed a dinner cabaret club, which they called the Thirteen Club. At the first meeting, on January 13, 1881, at 8:13 p.m., thirteen people sat down to dine in Room 13 of the venue. The guests walked under a ladder to enter the room and were seated among piles of spilled salt. Many "Thirteen Clubs" sprang up all over North America over the next 45 years. Their activities were regularly reported in leading newspapers, and their numbers included five future US presidents, from Chester A. Arthur to Theodore Roosevelt. Thirteen Clubs had various imitators, but they all gradually faded due to a lack of interest. The British submarine HMS K13 sank on 29 January 1917 while on her trials after diving with a hatch and some vents still open. Although she was raised and 48 men were rescued, 32 sailors and civilian technicians died. When repaired, she was renamed K22 but was later involved in multiple collisions with other K-class submarines on 1 February 1918 in which a total of 103 men were killed, an event known as the Battle of May Island. In the subsequent British L-class submarine, the number L13 was not used. Apollo 13 was launched on April 11, 1970, at 13:13:00 CST and suffered an oxygen tank explosion on April 13 (although this was not a Friday) at 21:07:53 CST, forcing it to abort its mission to land on the Moon. All crew returned safely to Earth on April 17. The Friday the 13th mini-crash was a stock market crash that occurred on Friday, October 13, 1989. Vehicle registration plates in Ireland are such that the first two digits represent the year of registration of the vehicle (i.e., 11 is a 2011 registered car, 12 is 2012, and so on). In 2012, there were concerns among members of the Society of the Irish Motor Industry (SIMI) that the prospect of having "13" registered vehicles might discourage motorists from buying new cars because of superstition surrounding the number thirteen, and that car sales and the motor industry (which was already doing badly) would suffer as a result. The government, in consultation with SIMI, introduced a system whereby 2013 registered vehicles would have their registration plates' age identifier string modified to read "131" for vehicles registered in the first six months of 2013 and "132" for those registered in the latter six months of the year.1
Effect on US space program mission naming
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![Triskaidekaphobia: Alternate mission patch of STS-41C, with a 13 and a black cat, as it landed on April 13th, which was a Friday the 13th and this was the mission originally scheduled as STS-13[17]](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b8/STS-41-c_Alt_Patch.jpg/330px-STS-41-c_Alt_Patch.jpg?utm_source=en.wikipedia.org&utm_campaign=parser&utm_content=thumbnail)

