Mucus or Mucous?

Our Story

Mucus or Mucous?

What is the difference between "mucous" and "mucus"?
  • "Mucus" is a noun. "Mucus" is a slimy substance secreted by the mucous membranes and glands.
    • In the human respiratory system, mucus aids in the protection of the lungs.
  • "Mucous" is an adjective. "Mucous" means producing or secreting mucus.
    • Some mucous membranes are involved with absorption and secretion.
mucus or mucous?
Got it? Take a quick test.

More about "Mucous"

The adjective "mucous" means covering or secreting mucus. It usually modifies the noun "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.

More about "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.

UK or US Spelling?

The spelling of "mucus/mucous" is determined by whether the word is used as a noun or an adjective. The spelling is not determined by whether you're following US or UK writing conventions. In other words, "mucus/mucous" is not like pairings such as "color/colour," "favor/favour," and "neighbor/neighbour".
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.

Help Us To Improve Grammar Monster

  • Do you disagree with something on this page?
  • Did you spot a typo?
Please tell us using this form.

See Also

adverse or averse? affect or effect? appraise or apprise? avenge or revenge? bare or bear? complement or compliment? dependant or dependent? discreet or discrete? disinterested or uninterested? e.g. or i.e.? envy or jealousy? imply or infer? its or it's? material or materiel? poisonous or venomous? practice or practise? principal or principle? tenant or tenet? who's or whose? What are nouns? What are adjectives? List of easily confused words