Agnosia is a rare disorder characterized by the inability to recognize and identify objects or people. People suffering from agnosia may have difficulty recognizing the geometric features of an object or face, or may be able to perceive 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 recognizing an object as a cup, or identifying a sound as a cough. Agnosia can result from strokes, dementia, developmental disorders, or other neurological conditions. It typically results from damage to specific areas in the occipital or parietal lobes of the brain. People with agnosia may retain their cognitive abilities in other areas.
This answer is based on source information from the National Institute of Neurological Disorders and Stroke.