encephalitis

noun

en·​ceph·​a·​li·​tis in-ˌse-fə-ˈlī-təs 

plural encephalitides in-ˌse-fə-ˈli-tə-ˌdēz 

: inflammation of the brain that is caused especially by infection with a virus (such as herpes simplex or West Nile virus) or less commonly by bacterial or fungal infection or autoimmune reaction

Note: Encephalitis may be asymptomatic or present with mild to severe symptoms (such as fever, headache, confusion, seizures, or loss of consciousness) sometimes progressing to coma or death.

encephalitic

in-ˌse-fə-ˈli-tik 

adjective

Examples of encephalitis in a Sentence

Recent Examples on the Web

The other deaths were in patients with cancers, encephalitis, respiratory failure, and septic shock. — Beth Mole, ArsTechnica, 7 Aug. 2026

Most people face a low risk of serious illness, but fewer than 1% develop severe neurological conditions such as encephalitis or meningitis. — Cecilio Padilla, CBS News, 5 Aug. 2026

Measles hospitalizes nearly 10% of its victims and causes pneumonia, sepsis and potentially fatal encephalitis. — Dr. Michael Good, Hartford Courant, 26 July 2026

Some people with measles require hospitalization, can develop pneumonia or encephalitis, which can cause brain damage and long-term cognitive impairment, and severe measles can lead to death, Joshi and other health experts warn. — Francine Knowles, Chicago Tribune, 20 July 2026

Word History

First Known Use

1843, in the meaning defined above

Phrases Containing encephalitis

• Eastern equine encephalitis
• equine encephalitis
• Powassan encephalitis
• Saint Louis encephalitis
• St. Louis encephalitis
• Venezuelan equine encephalitis
• Western equine encephalitis
• West Nile encephalitis

Rhymes for encephalitis

• alveolitis
• bronchiolitis
• caenorhabditis
• cholecystitis
• endometritis
• endophthalmitis
• folliculitis
• periostitis
• peritonitis
• polyneuritis
• thrombophlebitis
• adenitis

Kids Definition

encephalitis

noun

en·​ceph·​a·​li·​tis in-ˌsef-ə-ˈlīt-əs 

(ˌ)en-

: inflammation of the brain

also : a disease marked by encephalitis

Medical Definition

encephalitis

noun

en·​ceph·​a·​li·​tis in-ˌsef-ə-ˈlīt-əs 

plural encephalitides -ˈlit-ə-ˌdēz 

: inflammation of the brain that is caused especially by infection with a virus (such as herpes simplex, varicella zoster, or West Nile virus) or less commonly by bacterial or fungal infection or autoimmune reaction

Note: Encephalitis may be asymptomatic or present with mild to severe symptoms (such as fever, headache, confusion, seizures, or loss of consciousness) sometimes progressing to coma or death.

encephalitic

-ˈlit-ik 

adjective