Agoraphobia
Agoraphobia ("fear of the marketplace" in Greek) is an anxiety disorder characterized by intense fear of being caught or trapped in situations where no help is available should some incapacitating (e.g., losing control) or embarrassing (e.g., fainting) event occur in the presence of others.Agoraphobia can be brought on by repeated panic attacks and over time, if untreated, can lead to the fear of leaving one's house. Agoraphobia can also lead to depression.
For more information anxiety disorders in general or agoraphobia, see NIMH Anxiety Disorders and MedlinePlus Medical Encyclopedia: Agoraphobia.