en·​do·​the·​li·​um | \ˌen-də-ˈthē-lē-əm, -dō-\
plural endothelia\ ˌen-​də-​ˈthē-​lē-​ə , -​dō-​ \

Definition of endothelium 

1 : an epithelium of mesodermal origin composed of a single layer of thin flattened cells that lines internal body cavities and the lumens of vessels

2 : the inner layer of the seed coat of some plants

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Other Words from endothelium

endothelial \ ˌen-​də-​ˈthē-​lē-​əl , -​dō-​ \ adjective

Examples of endothelium in a Sentence

Recent Examples on the Web

Abnormalities in the endothelium, or inner lining, of these smaller vessels can cause spasms, resulting in pain and diminished blood flow to the heart. Roni Caryn Rabin, New York Times, "Is Microvascular Heart Disease a Serious Condition?," 29 Sep. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'endothelium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of endothelium

1872, in the meaning defined at sense 1

History and Etymology for endothelium

New Latin, from end- + -thelium (as in epithelium)

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Time Traveler for endothelium

The first known use of endothelium was in 1872

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More Definitions for endothelium


en·​do·​the·​li·​um | \ˌen-də-ˈthē-lē-əm \
plural endothelia\ -​lē-​ə \

Medical Definition of endothelium 

: an epithelium of mesoblastic origin composed of a single layer of thin flattened cells that lines internal body cavities (as the serous cavities or the interior of the heart)

More from Merriam-Webster on endothelium

Britannica.com: Encyclopedia article about endothelium

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