The human body produces many fluids. Some of these fluids are mundane and some inspire disgust, but they are all necessary for the body’s daily operation and maintenance. One such fluid is found in many membranes in various places throughout the body, but it is most commonly seen dripping from or being sneezed out of someone’s nose. We have a word for this substance, but how should we spell it? Is mucous or mucus the correct spelling?
Mucus as noun:
Mucus without the o, is used as a noun in English language where it refers to a slimy substance, typically not miscible with water, secreted by the mucous membranes and glands of animals for lubrication, protection, etc.
In certain medical contexts, a ball of mucus might be called a mucous ball. In this case, even though the ball itself is made up of mucus, mucous–not mucus–takes the function of an adjective. Mucous describes an attribute of the ball, therefore, a mucous ball and a mucous membrane.
Mucous as adjective:
Mucus or mucous:
Mucus and mucous are so similar in spelling, and pronunciation that people sometimes mix them up. Mucous is an adjective. It describes certain membranes in the body. For example, a mucous membrane. Mucus is a noun. It refers to the fluid secreted by these membranes. Mucous is only an adjective, and mucus is only a noun. Mucous has the traditional -ous ending shared by many adjectives. Armed with this fact, you shouldn’t have trouble choosing mucus or mucous in your writing.