Phobia

A phobia is an anxiety disorder, defined by an irrational, unrealistic, persistent and excessive fear of an object or situation. Phobias typically result in a rapid onset of fear and are usually present for more than six months. Those affected go to great lengths to avoid the situation or object, to a degree greater than the actual danger posed. If the object or situation cannot be avoided, they experience significant distress. Other symptoms can include fainting, which may occur in blood or injury phobia, and panic attacks, often found in agoraphobia and emetophobia.

From Wikipedia