Lymphocytic choriomeningitis (LCM) is a rodent-borne viral infectious disease that presents as aseptic meningitis, encephalitis or meningoencephalitis. Its causative agent is lymphocytic choriomeningitis mammarenavirus (LCMV), a member of the family Arenaviridae. The name was coined by Charles Armstrong in 1934.

Lymphocytic choriomeningitis (LCM) is "a viral infection of the membranes surrounding the brain and spinal cord and of the cerebrospinal fluid". The name is based on the tendency of an individual to have abnormally high levels of lymphocytes during infection. Choriomeningitis is "cerebral meningitis in which there is marked cellular infiltration of the meninges, often with a lymphocytic infiltration of the choroid plexuses".