Extreme and irrational fear of a particular object, class of objects, or situation. A phobia is classified as a type of anxiety disorder (a neurosis), since anxiety is its chief symptom. Phobias are generally believed to result when fear produced by an original threatening situation (such as a near-drowning in childhood) is transferred to other similar situations (such as encounters with bodies of water), the original fear often being repressed or forgotten. Behaviour therapy can be helpful in overcoming phobias, the phobic person being gradually exposed to the anxiety-provoking object or situation in a way that demonstrates that no threat really exists.

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