A disorder characterized by a change in the sense of smell. [CTCAE] Loss of or impaired ability to smell. This may be caused by OLFACTORY NERVE DISEASES; PARANASAL SINUS DISEASES; viral RESPIRATORY TRACT INFECTIONS; CRANIOCEREBRAL TRAUMA; SMOKING; and other conditions. | Absence of the sense of smell. (Dorland, 27th ed) [MeSH]