In medicine, to make (a person, animal, or tissue) nonreactive or nonallergic to a substance by removing the antibodies from affected cells or tissues: In an effort to control his allergies, Jason and the doctor went through a process of desensitization to eliminate the antibodies that were causing his sneezing.

In psychiatry, a form of behavior therapy in which the patient, while made to relax in comfortable surroundings, is gradually exposed to increasing amounts of anxiety-provoking stimuli: During reciprocal inhibition and desensitization, the patient can learn to tolerate these stimuli and may eventually learn to dissociate the anxiety from them.