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.
Examples of encephalitis in a Sentence
Recent Examples on the Web
Measles, one of the world’s most contagious infectious diseases, can cause serious complications – such as blindness, pneumonia or encephalitis, swelling of the brain – and even turn deadly, especially in children younger than 5.
—
Jacqueline Howard, CNN, 19 Feb. 2025
Measles infections can have serious complications, including blindness, pneumonia, or encephalitis (swelling of the brain).4
In some cases, these complications can be fatal.
—Jenna Anderson, Health, 14 Feb. 2025
Though rare in adults, complications of pertussis can include pneumonia, encephalitis (brain inflammation), and seizures.
—Erica Sloan, SELF, 13 Feb. 2025
In August of that year, the New York City Department of Health identified eight people with severe encephalitis (brain inflammation) within a 16-square mile area around Queens.
—Ars Technica, 20 Jan. 2025
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Jacqueline Howard, CNN, 19 Feb. 2025
Measles infections can have serious complications, including blindness, pneumonia, or encephalitis (swelling of the brain).4
In some cases, these complications can be fatal.
—Jenna Anderson, Health, 14 Feb. 2025
Though rare in adults, complications of pertussis can include pneumonia, encephalitis (brain inflammation), and seizures.
—Erica Sloan, SELF, 13 Feb. 2025
In August of that year, the New York City Department of Health identified eight people with severe encephalitis (brain inflammation) within a 16-square mile area around Queens.
—Ars Technica, 20 Jan. 2025
See All Example Sentences for encephalitis
Cite this Entry
“Encephalitis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/encephalitis. Accessed 3 Mar. 2025.
Copy CitationKids 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.
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