Definition of pus
: a thick, opaque, usually yellowish-white, fluid matter that is formed as part of an inflammatory response typically associated with an infection and is composed of exudate chiefly containing dead white blood cells (such as neutrophils), tissue debris, and pathogenic microorganisms (such as bacteria)
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
Slippery Words Quiz—Changing with the Times
- What is an earlier meaning of nice?

Can you spell these 10 commonly misspelled words?
TAKE THE QUIZ
Anagram puzzles meet word search.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridgedWords at Play
Ask the Editors
Word Games
Slippery Words Quiz—Changing with the Times
Do you know these earlier meanings of words?
Take the quizWords of Snow and Ice Quiz
A selection of words from the chillier parts of t...
Take the quizSpell It
Can you spell these 10 commonly misspelled words?
Take the quizSCRABBLE® Sprint
SCRABBLE® fans, sharpen your skills!
Play the game
Share pus
Time Traveler for pus
The first known use of pus was in the 15th century
See more words from the same century