mucus

noun

mu·​cus ˈmyü-kəs 

: 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

In fact, many of your symptoms like mucus production are actually your immune system’s reactions to the virus. —Bruce Y. Lee, Forbes.com, 24 Jan. 2026

So, measles showing up in wastewater is a sign that infected people are shedding tiny bits of the virus through things like mucus, saliva and stool. —Charlotte Observer, 23 Jan. 2026

Both cedar fever and many viral infections can cause clear, runny mucus. —Miriam Fauzia, Dallas Morning News, 20 Jan. 2026

In medicine, mucilage can act as a demulcent, a substance that soothes irritated mucus membranes by forming a protective layer over them. —Andrew Coletti, Popular Science, 14 Jan. 2026

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

Rhymes for mucus

• fucus
• mucous
• caducous
• sambucus
• submucous
• verrucous

Kids Definition

mucus

noun

mu·​cus ˈmyü-kəs 

: a slippery sticky substance produced especially by mucous membranes which it moistens and protects

Medical Definition

mucus

noun

mu·​cus ˈmyü-kəs 

: a viscid slippery secretion that is usually rich in mucins and is produced by mucous membranes which it moistens and protects