Triskadekaphobia

Triskaidekaphobia ( /ˌtrɪskaɪˌdɛkəˈfoʊbiə, ˌtrɪskə-/, TRIS-kye-DEK-ə-FOH-bee-ə or TRIS-kə-DEK-ə-FOH-bee-ə; from Greek triskaideka = “thirteen” (tris = “three” + kai = “and” + deka = “ten”) + phobos = “fear”) is fear or avoidance of the number 13. It is also a reason for the fear of Friday the 13th, called paraskevidekatriaphobia (from Παρασκευή Paraskevi, Greek for Friday) or friggatriskaidekaphobia (after Frigg, the Norse goddess after whom Friday is named in English).

The term was used as early as in 1910 by Isador Coriat in Abnormal Psychology.

From the 1890s, a number of English language sources relate the "unlucky" thirteen to an 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. Also, the number 13 is not uniformly bad in the Judeo-Christian tradition. For example, the attributes of God (also called the Thirteen Attributes of Mercy) are enumerated in the Torah (Exodus 34:6–7).

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