triskaidekaphobia \tris-ky-dek-uh-FOH-bee-uh\, noun: A morbid fear of the number 13 or the date Friday the 13th.Obviously, the reasons for regarding Friday the 13th to be unlucky are no less foolish than most other superstitious or religious "reasoning." But if superstitious we must be, how about if we regard Friday the 13th as a powerful day, a good day to take off and do something for ourself or someone else?
Examples:Thirteen people, pledged to eliminate triskaidekaphobia, fear of the number 13, today tried to reassure American sufferers by renting a 13 ft plot of land in Brooklyn for 13 cents...a month. – Daily Telegraph, January 14, 1967Triskaidekaphobia is from Greek treiskaideka, triskaideka, thirteen (treis, three + kai, and + deka, ten) + phobos, fear. In Christian countries the number 13 was considered unlucky because there were thirteen persons at the Last Supper of Christ. Fridays are also unlucky, because the Crucifixion was on a Friday. Hence a Friday falling on the thirteenth day is regarded as especially unlucky. Some famous triskaidekaphobes: Napoleon, Herbert Hoover, Mark Twain, Richard Wagner, Franklin Roosevelt. – "It's just bad luck that the 13th is so often a Friday," Electronic Telegraph, September 8, 1996
Past disasters linked to the number 13 hardly help triskaidekaphobics overcome their affliction. The most famous is the Apollo 13 mission, launched on April 11, 1970 (the sum of 4, 11 and 70 equals 85 - which when added together comes to 13), from Pad 39 (three times 13) at 13:13 local time, and struck by an explosion on April 13. – "It's just bad luck that the 13th is so often a Friday," Electronic Telegraph, September 8, 1996
And of course the frequency of Fridays' the 13th has nothing to do with luck, but with the mathematical logic of our Gregorian calendar....