Agoraphobia refers to the fear of public places or open spaces; agoraphobics try to avoid being in situations from which they think escape would be difficult or help and safety are not readily available; this is often diagnosed in conjunction with panic disorder
Other definition:
Agoraphobia refers to the intense Anxiety about being trapped or stranded in a situation without help if a panic attack occurs.
It is an Anxiety about being in places or situations from which escape might be difficult or embarrassing, or in which help may be unavailable in the event of a panic attack. It is an abnormal and persistent fear of public places or open areas, especially those from which escape could be difficult or help not immediately accessible. Persons with agoraphobia frequently also have panic disorder.
Based on the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision, also known as the DSM-IV-TR, patients with Agoraphobia are typically afraid of such symptoms as feeling dizzy, having an attack of diarrhea, fainting, or "going crazy."
Other /More definition:
Agoraphobia refers to anxiety about being in places or situations from which escape might be difficult. It is a a form of anxiety characterized by a fear of being alone in, and avoiding, certain places or situations from which escape may be difficult or embarrassing, or in which help may be unavailable in the event of a panic attack. Moreover, Agoraphobiais an abnormal and persistent fear of public places or open areas, especially those from which escape could be difficult or help not immediately accessible. Persons with agoraphobia frequently also have panic disorder