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

As well as hospitalization and death caused by complications — including pneumonia, encephalitis, diarrhea and dehydration — measles can cause long-term, debilitating health complications such as cognitive impairment and blindness. —Sarah Ferguson, Forbes.com, 4 Apr. 2025

Serious complications, especially in children under 5, can include ear infections, diarrhea, pneumonia and encephalitis. —Matt Leclercq, Fort Worth Star-Telegram, 28 Mar. 2025

One in 1,000 will develop encephalitis, or swelling of the brain, which can lead to permanent hearing loss and intellectual disabilities. —Tom Zirpoli, Baltimore Sun, 25 Mar. 2025

Serious complications include pneumonia and encephalitis. —Ian Randall, MSNBC Newsweek, 24 Apr. 2025

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
• conjunctivitis
• endometritis
• endophthalmitis
• esophagitis
• folliculitis
• myocarditis
• periostitis
• peritonitis

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