What does mucus mean?
Mucus is a thick, slippery, gel-like substance produced by the body, especially in the nose, mouth, respiratory tract, and other internal surfaces. It helps trap dust and microorganisms, moisten and protect tissues, and carry or lubricate material through the body. In everyday medical contexts, mucus often refers to material produced during a cold, cough, or other respiratory infection. The word also has a zoological sense: snails, slugs, and related animals secrete mucus for movement, protection, and the formation of trails. Although mucus is closely associated with disease or illness when it becomes excessive, it is also a normal and necessary bodily secretion. The related adjective “mucous” appears in anatomical terms such as “mucous membrane,” while “mucosal” is used in more technical medical language. Mucus should not be confused with mucin, which is one of the specific protein-rich components found within many mucus secretions.
nounA thick, slippery, gel-like secretion produced by the body, especially in the nose and respiratory tract. The term also refers to the slimy material secreted by snails and other molluscs.
- A thick, viscous secretion of the body, especially one produced in the nose or respiratory tract.
- A slimy or gelatinous substance secreted by certain animals, particularly snails and other molluscs.
"A blocked nose can make it difficult to breathe through the thick mucus."
"She gently wiped the mucus from the child's nose."
"The snail left a shining trail of mucus across the garden path."
Mucus is normally used as a mass noun and has no plural. The rare plural “mucuses” is used when separate portions or masses of mucus are being counted.
"Small mucuses had collected around the opening."
The familiar trail left by a snail is mucus—a useful substance that helps it move while also protecting its body from drying out and harmful substances.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does mucus come from?
The English word comes through Latin from mucus, meaning a viscous secretion or slimy bodily fluid. The Latin term also underlies words including mucosa, mucosal, mucous, and mucin. Its development reflects the longstanding association between mucus with both protective bodily secretions and the slippery material produced by molluscs.
How mucus is actually used
In medical and everyday use, “mucus” usually names the secretion itself. The adjective “mucous” is common in anatomical expressions such as “mucous membrane,” while “mucosal” also occurs in medical terminology.
Easily confused with mucus
“Mucus” is the noun naming the secretion, whereas “mucous” is an adjective describing something that produces or contains mucus.
Mucus is the complete bodily secretion, while mucin is a specific glycoprotein component found within it and in similar secretions.