Agnosia: The inability to recognize and identify objects or persons despite having knowledge of the characteristics of those objects or persons. People with agnosia may have difficulty recognizing the geometric features of an object or face or may be able to perceive the geometric features but not know what the object is used for or whether a face is familiar or not. Agnosia can be limited to one sensory modality such as vision or hearing. For example, a person may have difficulty in recognizing an object as a cup or identifying a sound as a cough. Agnosia can result from strokes, dementia, or other neurological disorders. It typically results from damage to specific brain areas in the occipital or parietal lobes of the brain. People with agnosia may retain their cognitive abilities in other areas.