Triskaideka comes from the Greek words tris meaning “3”, kai meaning “and”¸ and deka meaning “10” and trikaidekaphobia is the irrational fear of the number 13. This term was first coined by Isador Coriat in the book Abnormal Psychology and is related to the fear of Friday the 13th called paraskevidekatriaphobia or friggartriskaidekaphobia.
The myth that the number 13 is unlucky or evil dates back in 1780 BC when the 13th law was omitted in the Babylonian Code of Hammurabi. Other causes of this fear include the 13th disciple was the one who betrayed Jesus, Ancient Persians believing that 12 constellations in the Zodiac controlled the 12 months of the year and having a 13th month would mean chaos in the sky and the earth.
We can see this fear in our everyday life wherein most tall buildings do not have a 13th floor, or skip the number 13 when numbering the floors of the building. Hospitals, hotels, offices and other establishments skip the number 13 because of the fear of something terrible happening in that room. Although there is no rational evidence to support that the number 13 is indeed unlucky, this has been practiced in many countries worldwide and has become a part of our culture.
Those who fear the number 13 can show signs and symptoms of anxiety and treatment includes behavioral therapy. Medications may be given to alleviate symptoms of extreme anxiety.