Enneaphobia

Nonaphobia is an abnormal fear of the number nine. It is a rare phobia and it is not recognize by the medical literature. The term comes from the Greek nona meaning nine, and phobos meaning fear.

Nonaphobia may be triggered due to superstitions or frequently failing tests or competitions at one away from completion, like achieving 9/10 in the quiz, achieving 99% in the video game but couldn't go any further, or even seeing a grandparent or great-grandparent dying at age 99. 99-year olds may commonly have this fear until they make it to 100. The fear could even be due to some mathematical uniqueness of the number nine, like dividing number by nine or nine-only number (e.g. 999) whose both numbers containing same number of digits would result in the number repeating itself, leading them to have negative thought about infinity and possibly leading to apeirophobia.

Nonaphobia is usually not a severe phobia, but it sufferers would often avoid the triggers. Nonaphobes would try to avoid encountering the number that ends with nine especially, e.g. 39, 449. A nonaphobe may not like to live in the house that has the address ending with nine. Sufferers may not mind to chronologically assign the age ending with nine.