No, the word "Hexakosioihexekontahexaphobia" is not found in the Webster's 3rd New International Dictionary.

"Hexakosioihexekontahexaphobia" is a fear of the number 666, and is Biblical in its origins. There are questions as to weather hexakosioihexekontahexaphobia should actually be classified as a phobia because it is not an object or situation.

It is believed that this fear is more common than one would initially expect (it is similar to the fear of the number 13) but there is no way to tell you how many people suffer from it.

hex ako sio oi hex eko nta hex a phobia

Hexakosioihexekontahexaphobia is the fear of the number 666. It is a specific phobia that stems from superstitions and religious beliefs associating the number with evil or the devil, particularly in Christian theology based on the Book of Revelation.

The fear of the number 666 is called Hexakosioihexekontahexaphobia - and thus its sufferers are Hexakosioihexekontahexaphobics.