Tris (greek for three) deka (greek for 10) phobe (an individual affected by a certain fear) effectivey a triskaidekaphobe fears the number thirteen, or situation that involves anything in a 13 sequence... When a group of 13 objects is divided into two, three, four or six equal groups, there is always one leftover object. it is believed that Loki in the Norse pantheon was the 13th god. This was later Christianised into saying that Satan was the 13th angel. in a lunar calender there are 13 months as there are thirteen full moons a year, however the christian calender is only 12 months long... often times elevators in taller buildings skip the number 13.... the folloing is from wikipedia.com: The composer Arnold Schoenberg suffered from triskaidekaphobia. It is said that the reason his late opera is called Moses and Aron, rather than Moses and Aaron (the correct spelling with two As) is because the latter spelling has thirteen letters in it. He was born (and, it turned out, died) on the thirteenth of the month, and thought of this as a portent. He once refused to rent a house because it had the number 13, and feared turning 76, because its digits add up to thirteen. In an interesting story, it is believed that he feared Friday, July 13, 1951, as it was the first Friday the 13th of his 76th year. He reportedly stayed in bed that day preparing for what he thought as his death day. After begging her husband to wake up and "quit his nonsense," his skeptical wife was shocked when...