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

An orangutan at the Little Rock Zoo died earlier this week of encephalitis, the zoo said in a news release. —Harley Walls, Arkansas Online, 28 June 2025

Bruxism has been associated with a number of chronic health conditions, including Parkinson's disease, encephalitis, epilepsy, traumatic brain injury and hyperthyroidism, says Schultz. —Caroline C. Boyle, USA Today, 1 June 2025

Serious complications, especially in kids under 5, can include ear infections, diarrhea, pneumonia and encephalitis. —Matt Leclercq, Fort Worth Star-Telegram, 1 Apr. 2025

Complications can include acute encephalitis that causes brain inflammation, blindness, ear infections, diarrhea and pneumonia. —Anna Spiegel, Axios, 24 Mar. 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