a yellow-white, more or less viscid substance produced by suppuration and found in abscesses, sores, etc., consisting of a liquid plasma in which white blood cells are suspended.
late 14c., from Latin pus "pus, matter from a sore;" figuratively "bitterness, malice" (related to puter "rotten;" cf. putrid), from PIE *pu- (2) "to rot, decay" (cf. Sanskrit puyati "rots, stinks," putih "stinking, foul;" Greek puon "discharge from a sore," pythein "to cause to rot;" Gothic fuls, Old English ful "foul"), perhaps originally echoic of a natural exclamation of disgust.
