mucus

American  

[myoo-kuhs] / ˈmju 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

See Examples For:

mucus

Cilia, tiny hairs that clear mucus out of the lungs, resume working within weeks, prompting coughing that clears the lungs.

From The Wall Street Journal ● Jul. 23, 2026

What’s more, staying hydrated helps flush toxins, keeps organs functioning optimally and thins mucus, making it easier for lungs to stay clear.

From The Wall Street Journal ● Jul. 23, 2026

When Howard was seven years old, he was diagnosed with cystic fibrosis, the genetic condition that causes sticky mucus to build up in the lungs and digestive system.

From BBC ● Jul. 14, 2026

Ranchers have to remove eggs and larvae and disinfect and treat wounds, infected ears or mucus membranes.

From MarketWatch ● Jun. 10, 2026

I stroll back to 315, coughing when I get there, the mucus thick in my lungs and throat, my chest aching from my excursion.

From "Five Feet Apart" by Rachael Lippincott

Related Words

• goo
• gunk
• mud
• sludge