Anything neurological has to do with the nervous system — the brain, spinal cord, or nerves. A neurological disorder might affect a person's memory or the quality of their sleep.
Neurological tests are used by doctors to see how well the patient's nervous system is working, and they involve things like balance, memory, and strength. A neurological illness can affect the brain, like Alzheimer's Disease, or coordination of the muscles, like Cerebral Palsy. Neurological and neurology, the study of the nervous system, come from Greek roots neuro, "pertaining to a nerve," and logia, "study."