What does pus mean?
Pus is the thick fluid that can accumulate during inflammation, most often in response to infection. It commonly appears pale yellow or cream, though its appearance can vary, and consists largely of fluid, white blood cells, broken-down tissue, and often microorganisms. The word is especially common in medical descriptions of infected wounds, abscesses, and boils, as well as in general discussion of the body's response to injury or disease. Although pus is usually associated with infection, it is not itself a synonym for infection, since sterile inflammation can also produce it. In standard English, pus is generally uncountable, so articles and plural forms are unnecessary when referring to the substance. Related words include purulent, meaning containing or consisting of pus, and suppurate, meaning to form or discharge pus. The vocabulary is useful because it identifies a distinctive and familiar part of the inflammatory process while connecting everyday language with formal medical terminology.
nounA thick, usually pale yellow or cream-coloured fluid produced by inflammation, especially in an infected wound or abscess. It consists of fluid, white blood cells, dead tissue, and microorganisms.
- A fluid produced by inflammation, particularly in an infected wound, sore, or abscess.
"The doctor drained the abscess after examining the surrounding swelling and pus."
"There was a bead of pus at the edge of the wound."
"The sample was sent for testing because it contained pus."
"The boil had produced a large pocket of pus."
Pus is normally an uncountable mass noun, so a plural form is not used in standard English.
"The surgeon removed the pocket of pus."
Pus comes straight from Latin pus, puris—some vocabulary is more honest than polite.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does pus come from?
The word comes from Latin pus, puris, meaning pus or a similar purulent fluid. It entered English during the early modern period and has remained a direct borrowing rather than undergoing substantial grammatical change. English forms such as purulent and suppurate were likewise developed from Latin words associated with pus, while pustule comes from the related Latin term pustula.
How pus is actually used
In medical and biological contexts, pus is normally treated as an uncountable mass noun. The term is clinically specific and is less suitable than exudate, discharge, or inflammation in general discussion.
Easily confused with pus
Pus is an inflammatory bodily fluid, whereas puss can mean a cat or, informally, anger or a cat-like person.