n. inflammation of the brain, typically caused by viral infection. The symptoms may be mild, with influenza-like characteristics, or severe and potentially fatal, with fever, vomiting, confusion or disorientation, drowsiness, seizures, and coma or loss of consciousness. See also encephalitis lethargica; herpes-simplex encephalitis; meningoencephalitis; polioencephalitis. —encephaliticadj.