Mucus vs. Sputum — What's the Difference?

Mucus ( MEW-kəs) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells.

Sputum is mucus that is coughed up from the lower airways (the trachea and bronchi). In medicine, sputum samples are usually used for naked eye exam, microbiological investigations of respiratory infections and cytological investigations of respiratory systems.

The viscous, slippery substance that consists chiefly of mucin, water, cells, and inorganic salts and is secreted as a protective lubricant coating by cells and glands of the mucous membranes.

Matter coughed up and usually ejected from the mouth, including saliva, foreign material, and substances such as mucus or phlegm, from the respiratory tract.

(physiology) A slippery secretion from the lining of the mucous membranes.

(physiology) Matter coughed up and expectorated from the mouth, composed of saliva and discharges from the respiratory passages such as mucus, phlegm or pus.

A viscid fluid secreted by mucous membranes, which it serves to moisten and protect. It covers the lining membranes of all the cavities which open externally, such as those of the mouth, nose, lungs, intestinal canal, urinary passages, etc.

That which is expectorated; a salival discharge; spittle; saliva.

Any other animal fluid of a viscid quality, as the synovial fluid, which lubricates the cavities of the joints; - improperly so used.

Expectorated matter; saliva mixed with discharges from the respiratory passages; in ancient and medieval physiology it was believed to cause sluggishness

A gelatinous or slimy substance found in certain algæ and other plants.

Protective secretion of the mucous membranes; in the gut it lubricates the passage of food and protects the epithelial cells; in the nose and throat and lungs it can make it difficult for bacteria to penetrate the body through the epithelium