Mucous

The adjective mucous means covering or secreting mucus. It is usually seen modifying the nouns gland or membrane. For example:
  • Mucous glands are found in several different parts of the body.
  • Sodium is excreted by all mucous surfaces and by the liver and kidneys.

Mucus

The noun mucus denotes a slimy substance that is produced by the mucous membranes and glands. For example:
  • Mucus production in humans thickens in cold weather.
  • Nasal mucus is usually clear and thin so it can filter air during inhalation.

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