Triskaidekaphobia

Triskaidekaphobia is the fear or avoidance of the number thirteen, its name drawn from the Ancient Greek words for thirteen and fear; the related fear specifically of Friday the thirteenth is known as paraskevidekatriaphobia or friggatriskaidekaphobia. The term itself is comparatively recent, used as early as 1910 by Isador Coriat in Abnormal Psychology, though the underlying superstition about thirteen being unlucky is older, with scholars tracing its earliest clear attestation in Europe to after the Middle Ages. Two main origin theories are commonly cited: one traces the association to tarot, where in 1781 Antoine Court de Gebelin described the Death card, numbered thirteen, as always regarded as unlucky, and the other points to the superstition, documented since at least 1774, that if thirteen people sit at a table together one of them will die within a year. The fear manifests practically across modern society, most visibly in buildings that omit a labeled thirteenth floor, skipping to fourteen or using an alternative designation, a practice followed by roughly 85 percent of buildings using Otis elevators according to the manufacturer's own data, and it even influenced institutional naming, as when NASA avoided the designation STS-13 for a Space Shuttle mission following the Apollo 13 disaster.