Paraskevidekatriaphobia: Fear of Friday the 13th. The word "paraskevidekatriaphobia" was devised by Dr. Donald Dossey who told his patients that "when you learn to pronounce it, you're cured!"
Triskaidekaphobia, fear of the number 13, is widely accepted among western cultures. Most hotels skip the 13th floor. Many airlines omit the 13th row. Some cities and towns skip over 13th Street. However, Friday the 13th is considered a particularly unlucky day. You undoubtedly are familiar with the movie franchise that has profited from the superstition surrounding it. The origins of this fear are unknown but are believe to be connected to the arrest of the Knights Templar on Friday, October 13, 1307.
On average, there is a Friday the 13th once every 212.35 days. This year, there are two. The next one will fall in November.