Mucus or Mucous?

by Craig Shrives

What Is the Difference between "Mucus" and "Mucous"?

"Mucus" and "mucous" are easy to confuse because they both refer to a slimy secretion. The difference between "mucus" and "mucous" is how they are used grammatically.
  • "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?

Top Tip

"Mucus" is a noun.

Q: What's a noun?
A: A noun names something.

"Mucous" is an adjective.

Q: What's an adjective?
A: An adjective describes something.

Nouns vs Adjectives

Look at this:
  • "Mucus" is to wood, Iraq, and navy as "mucous" is to wooden, Iraqi, and naval.
Read more about nouns and adjectives.

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. correct tick
  • Sodium is excreted by all mucous surfaces and by the liver and kidneys. correct tick

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. correct tick
  • Nasal mucus is usually clear and thin so it can filter air during inhalation. correct tick

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".

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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? lasagna or lasagne? What are adjectives? List of easily confused words