mucus

American  

[myoo-kuhs] / ˈmyu kəs /

noun

1. a viscous, slimy mixture of mucins, water, electrolytes, epithelial cells, and leukocytes that is secreted by glands lining the nasal, esophageal, and other body cavities and serves primarily to protect and lubricate surfaces.

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mucus British  

/ ˈmjuːkəs /

noun

1. the slimy protective secretion of the mucous membranes, consisting mainly of mucin

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mucus Scientific  

/ myo̅o̅′kəs /

1. The slimy, viscous substance secreted as a protective lubricant by mucous membranes. Mucus is composed chiefly of large glycoproteins called mucins and inorganic salts suspended in water.

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mucus Cultural  

1. A slippery and somewhat sticky fluid secreted by the glands in mucous membranes. Mucus lubricates and protects the mucous membranes.

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Etymology

Origin of mucus

1655–65; < Latin mūcus snot; akin to Greek myktḗr nose, mýxa slime

Compare meaning

How does mucus compare to similar and commonly confused words? Explore the most common comparisons:

• sputum vs. mucus

Explanation

Mucus is snot and other slime from inside your body. More specifically, mucus is a secretion of your body's mucus membranes that lubricates the inside of your body and helps protect you from bacteria. You’re welcome. Even the history of the word mucus is gross — roots from Greek and Latin all mean “snot” and “slippery, slimy.” Mucus drips out of your nose and even slips down your throat when you’re sick. This happens because your membranes produce too much mucus when you’re sick. Mucus isn’t all bad though — your body uses it to help food go down your throat easier, and it keeps bacteria out. Mucus is gross, but germs are worse!

Example Sentences

Born with cystic fibrosis, a genetic disorder that causes mucus to become thick and sticky, she has just 9% lung function.

From BBC • Mar. 24, 2026

CF is a genetic condition that can particularly affect someone's digestive system, as well as their lungs, because their body produces a thick, sticky mucus that coats the organs.

From BBC • Mar. 20, 2026

This sugar is commonly found in mucins, the molecules that form mucus.

From Science Daily • Mar. 16, 2026

Because the root problem is the loss of this protective mucus rather than sluggish intestinal movement, standard laxatives and drugs designed to stimulate gut motion may not provide relief.

From Science Daily • Feb. 19, 2026

He took a Q-Tip and rubbed it in the dead monkey’s throat, collecting a little bit of mucus, a throat wash.

From "The Hot Zone" by Richard Preston

Related Words

• goo
• gunk
• mud
• sludge