Complete or severe loss of the subjective sense of smell. Loss of smell may be caused by many factors such as cold, allergy, OLFACTORY NERVE DISEASES, viral RESPIRATORY TRACT INFECTIONS (e.g., COVID-19), aging and various neurological disorders (e.g., ALZHEIMER DISEASE).

Synonyms: Smell Loss, Hyposmia, Anosmia, Hyposmias, Loss of Smell