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  

/ ˌɛnsɛfəˈlaɪtɪs, ˌɛnkɛf- /

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

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Etymology

Origin of encephalitis

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

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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

There is, as Tbakhi experienced, a potential for continued complications—as well as long-term neuralgic pain called postherpetic neuralgia, blindness, and encephalitis.

From Slate ● Nov. 1, 2026

As the outbreak grows, doctors say they are seeing more patients with rare outcomes of the disease—things like severe pneumonia and encephalitis, a form of brain swelling that can lead to disabilities.

From The Wall Street Journal ● Oct. 7, 2026

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

Eastern equine encephalitis, caused by the prick of a mosquito, attacks the brain and central nervous system.

From "A Walk in the Woods" by Bill Bryson

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