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

Explanation

Encephalitis is a condition that causes the brain to swell and become irritated or inflamed. Most cases of encephalitis result from a virus. The term encephalitis comes from the Greek enkephalos, "brain," and the medical suffix -itis, used for diseases characterized by inflammation. Certain kinds of infections or disorders of the immune system can result in this inflammation of the brain. Encephalitis is quite rare, and though it's often so mild that it causes no symptoms, it can be serious.

Example Sentences

See Examples For:

encephalitis

In these cases, the virus affects the brain or nervous system and can cause encephalitis or meningitis, which can result in an infection of the brain or surrounding tissue.

From Los Angeles Times ● Jul. 8, 2026

The findings, published in Nature Communications, explain how viruses responsible for illnesses such as polio, encephalitis, myocarditis, and even the common cold take control of cellular machinery to copy themselves.

From Science Daily ● May 13, 2026

A CT scan later revealed brain inflammation, and on 12 September she was diagnosed with viral encephalitis.

From BBC ● Apr. 12, 2026

Doctors diagnosed her with encephalitis - an uncommon but serious condition in which the brain becomes inflamed or swollen, with one in five cases proving fatal.

From BBC ● Apr. 12, 2026

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