Mucous or Mucus?

Our most common search themes:
Question: What is the difference between mucous and mucus?

Answer: Mucous is an adjective. Mucus is a noun.

Mucous is an adjective meaning producing or secreting mucus.
  • Some mucous membranes are involved with absorption and secretion.
Mucus is a noun which denotes a slimy substance secreted by the mucous membranes and glands.
  • In the human respiratory system, mucus aids in the protection of the lungs.


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.


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.