platelet-activating factor
noun
plate·let-ac·ti·vat·ing factor
-ˌak-tə-ˌvāt-iŋ- 
: phospholipid that is produced especially by mast cells and basophils, causes the aggregation of blood platelets and the release of blood-platelet substances (as histamine or serotonin), and is a mediator of inflammation (as in asthma)
—abbreviation PAF
Cite this Entry
“Platelet-activating factor.” Merriam-Webster.com Medical Dictionary, Merriam-Webster, https://www.merriam-webster.com/medical/platelet-activating%20factor. Accessed 31 Oct. 2025.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
Share