Mucus vs Mucous: What’s The Difference?

Have you ever realized that there seem to be two different spellings of mucus? Did you get tripped up on trying to use it in a sentence and didn’t know which one was right or if they both were right? It actually turns out that mucus and mucous are both spelled correctly but are different words. One is an adjective and the other is a noun, be sure to read on to figure out which one is which and learn as much as you would ever want to learn about mucus. 

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What Is the Definition of the Word Mucus?

Let’s start by describing what mucus and mucous are and the definition of the word in its different forms.

Adjective Mucous

  • pertaining to, consisting of, or resembling mucus in the human body.
  • containing or secreting mucus.

Noun Mucus

  • a viscous, slimy mixture of mucins, water, electrolytes, enzymes, glycoproteins, epithelial cells, and white blood cells that is secreted by mucous glands lining the nasal, sinus, gastric, esophageal, and other body cavities and serves primarily to protect and lubricate surfaces. Mucous cells are involved in the immune system, the gastrointestinal/digestive system, and the respiratory system/respiratory tract. Allergens as well as pathogens can contribute to mucus production in the form of nasal mucus that can contribute to a runny nose or a cough with phlegm in the throat. 

What Is the Difference Between Mucus and Mucous?

Mucus is the noun whereas mucous is the adjective describing things pertaining to mucus. Many people will misspell mucus by spelling mucous when they are using it as a noun. Modern technology doesn’t help this since everyone relies on spell check to help aid them with their spelling and mucous is a word but it is an adjective. 

The History and Origin of the Word

The word mucus can be traced back to 1655. The use of the word was originally in Latin and meant snot. This was similar to the Greek word mykter which meant nose and myxa which meant slime. 

Examples of the Words in Context



Synonyms of Mucus

  • Sludge
    • mud, mire, or ooze; slush.
    • a deposit of ooze at the bottom of a body of water.
    • any of various more or less mudlike deposits or mixtures.
    • the sediment in a steam boiler or water tank.
    • broken ice, as on the sea.
    • a mixture of some finely powdered substance and water.
  • Mud
    • wet, soft earth or earthy matter, as on the ground after rain, at the bottom of a pond, or along the banks of a river; mire.
    • Informal. scandalous or malicious assertions or information:
    • The opposition threw a lot of mud at our candidate.
    • Slang. brewed coffee, especially when strong or bitter.
  • Goo
    • a thick or sticky substance:
      • Wash that goo off your hands.
  • Gunk
    • any sticky or greasy residue or accumulation:
      • gunk on the oil filter.
  • Saliva
    • a viscid, watery fluid, that the body produces in the mouth by the salivary glands, that functions in the tasting, chewing, and swallowing of food, moistens the mouth, and starts the digestion of starches.


Now you probably know more than you ever wanted to know about mucous and a lot of trivia/facts about the word.