encephalitis

American  

[en-sef-uh-lahy-tis] / ɛnˌsɛf əˈlaɪ tɪs /

noun

Pathology.

1. inflammation of the substance of the brain.

2. Also called encephalitis lethargica.  a form of this condition, caused by a filterable virus and characterized by apathy and abnormal sleepiness; sleeping sickness.

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encephalitis British  

/ ˌɛnkɛf-, ˌɛnsɛfəˈlaɪtɪs, ˌɛnsɛfəˈlɪtɪk /

noun

1. inflammation of the brain

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encephalitis Scientific  

/ ĕn-sĕf′ə-lī′tĭs /

1. Inflammation of the brain, usually caused by infection with a virus.

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encephalitis Cultural  

1. An inflammation of the brain. Encephalitis may be caused by a virus or lead poisoning, or it may be a complication of another disease, such as influenza or measles. Encephalitis can cause permanent brain damage or death. It is also possible, however, to recover from it completely.

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Other Word Forms

• encephalitic adjective
• postencephalitic adjective
• pseudoencephalitic adjective

Etymology

Origin of encephalitis

First recorded in 1835–45; encephal- + -itis

Example Sentences

There are allusions to the tragedies that befell him: the loss of a young daughter to measles encephalitis and his son’s near-fatal accident.

From The Wall Street Journal • Mar. 24, 2026

Certain Acanthamoeba species can cause serious illnesses, including amoebic encephalitis.

From Science Daily • Feb. 19, 2026

Measles can cause encephalitis, or inflammation of the brain.

From Los Angeles Times • Jun. 26, 2025

Measles is the most contagious infectious disease in the United States, and complications can be especially dangerous in older populations, causing serious conditions such as pneumonia and encephalitis, and even death.

From Salon • Apr. 15, 2025

Then there were all the diseases one is vulnerable to in the woods—giardiasis, eastern equine encephalitis, Rocky Mountain spotted fever, Lyme disease, ehrlichiosis, schistosomiasis, brucellosis, and shigellosis, to offer but a sampling.

From "A Walk in the Woods" by Bill Bryson