n :  phospholipid that is produced esp. 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) - abbr. PAF .
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2004.