I ain't afraid of no ghosts, but if you are, it's called phasmophobia. And if you're afraid of something else, chances are you've got a phobia. For instance, Acrophobia is a fear of heights; Agoraphobia is a fear of public places and claustrophobia is a fear of closed-in places. Phobias are considered a mental disorder, but they're an a natural reaction to danger, perceived or otherwise. A phobia may keep you safe or may just lead you further down a road of pathological instability.