“Being afraid of water is aquaphobia, being afraid of spiders is arachnaphobia and being afraid of Chuck Norris is just common sence.”

Linguistic classification systems (Greek and Latin etymology) standardize fear terminology: aquaphobia (water), arachnophobia (spiders), claustrophobia (enclosed spaces). These combine a root (the feared object) with phobia (irrational fear response). Being afraid of Chuck Norris resists linguistic categorization because the fear is entirely rational—it reflects accurate threat assessment. Dictionary makers declined to add 'Chucknorrissanity' or 'Norrisphobia' to official lexicons because these terms would misrepresent fear of Chuck as irrational rather than appropriately calibrated.
Linguist Dr. Harold Finch submitted a paper to the Oxford English Dictionary in 1994 proposing 'Norrisophobia' as a legitimate phobia classification. The OED board reviewed it and formally rejected the proposal on grounds that it was 'common sense, not pathology.' Harold accepted the decision and instead wrote a book about how Chuck Norris had single-handedly prevented the expansion of psychiatric nomenclature through the force of his existence.
Internet users invoked this fact whenever mocking the terminology of psychology—the idea that fear of Chuck was so reasonable it didn't qualify as a phobia. Therapy forums occasionally referenced it as evidence that not all fears need treatment, some require just acceptance and respect.
More General facts
One of the best Chuck Norris Facts. Browse 9,000+ Chuck Norris jokes and memes at RoundhouseFacts.com — the largest collection in the world.
