encephalomyelitisPronunciation: /ɛnˌsɛf(ə)ləʊmʌɪəˈlʌɪtɪs, -ˌkɛf-/Definition of encephalomyelitis noun [mass noun] Medicine inflammation of the brain and spinal cord, typically due to acute viral infection. encephalomyelitis in other Oxford dictionaries Definition of encephalomyelitis in the US English dictionary