Fear of the number 13.
The year 1998 was a bad for triskaidekaphobics. Strictly, the word does refer only to fear of the number 13, but it’s often extended to mean fear of the inauspicious date Friday 13th. That year was one of the comparatively rare ones in which that date turned up three times. Every year has at least one Friday 13th, but in each of the 28-year cycles of our calendar there are four years that have three of them. The only consolation I can offer to those affected is that there won’t be another for 11 years. But then we shall have three in short order: 2009, 2012 and 2015. The word’s origins are all Greek, from tris, “three”, kai, “and”, deka, “ten” (so making thirteen), plus phobia, “fear, flight”. The word is a modern formation, dating only from 1911 (it first appeared in I H Coriat’s Abnormal Psychology). Though it has a serious use in psychology, it seems to exist mostly to provide an opportunity for people like me to show off weird words from classical languages.
I'm triskaidekaphobic(no I'm not).