The belief in and even fear of the number 13 is not always a phobia. A true phobia, a condition like triskaidekaphobia, is an anxiety disorder that can be diagnosed.

After years of having a rather a strained relationship with Wimbledon thanks to being "paralysed by fear" at the thought of ...

In Italy, Friday the 17th is the day to fear, with 13 being considered a lucky number. In Spain, not Friday but Tuesday the 13th the unluckiest day. Checking the calendar for future Friday the 13ths.