The diagnosis brings together "Frigg," a Norse goddess and Friday's namesake, and  "triskaidekaphobia," fear of the number 13 in general.

Every year, the world loses $700 to $800 million on Friday the 13th because people won't conduct business as usual. Many especially refuse to fly.

On top of that, almost 80% of high rise buildings skip the 13th floor. Many airports exclude gate 13, and hospitals regularly avoid room 13.

So where does this superstition originate? The roots link back to religion — of all denominations and time periods.