Definition of panencephalitis in US English:

panencephalitis

noun

Medicine
  • Inflammation of white and grey matter of the brain; diffuse or generalized encephalitis; an instance of this; specifically (in full "subacute sclerosing panencephalitis") a chronic diffuse encephalitis causing progressive neurological deterioration and death, seen as a rare complication of measles virus infection, usually in children.

Origin

1950s; earliest use found in Brain: a journal of neurology. From pan- + encephalitis, after German Panencephalitis.