mucus

noun

mu·​cus ˈmyü-kəs How to pronounce mucus (audio)
: a viscid slippery secretion that is usually rich in mucins and is produced by mucous membranes which it moistens and protects

Examples of mucus in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Bronchial asthma, or simply asthma, is, according to the Cleveland Clinic, a chronic inflammatory disease of the airways that causes the breathing tubes in the lungs to swell, narrow, and produce extra mucus. — Greg Evans, Deadline, 17 Oct. 2026 In the human intestine, microorganisms are concentrated mainly in a mucus layer near the villi’s surface. — Neetika Walter, Interesting Engineering, 15 Oct. 2026 Lung adenocarcinoma begins in cells in the lung that make mucus, called epithelial cells, which line the surface of the lungs, the American Cancer Society says. — ABC News, 15 Oct. 2026 Guaifenesin may help relieve chest congestion by thinning mucus in your airways, says Reed. — Andee Tagle, NPR, 15 Oct. 2026 See All Example Sentences for mucus

Word History

Etymology

borrowed from Latin mūcus, muccus "nasal discharge," perhaps going back to *moukos, o-grade derivative of Indo-European *(s)muk- "nasal discharge," *(s)meuk- "undo, loosen, wipe off" — more at myxo-

Note: See note at myxo-.

First Known Use

1597, in the meaning defined above

Time Traveler
The first known use of mucus was in 1597

Rhymes for mucus

See All Rhymes for mucus

Browse Nearby Words

muculent
mucus
mud
See all Nearby Words

Cite this Entry

“Mucus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mucus. Accessed 27 Oct. 2026.

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Kids Definition

mucus

noun
mu·​cus ˈmyü-kəs How to pronounce mucus (audio)
: a slippery sticky substance produced especially by mucous membranes which it moistens and protects

Medical Definition

mucus

noun
mu·​cus ˈmyü-kəs How to pronounce mucus (audio)
: a viscid slippery secretion that is usually rich in mucins and is produced by mucous membranes which it moistens and protects

More from Merriam-Webster on mucus

Britannica.com: Encyclopedia article about mucus

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