pyo-

yellowish-white inflammatory exudation, consisting of white blood cells, etc., produced by suppuration, late 14c., from Latin pus "pus, matter from a sore;" figuratively "bitterness, malice" (related to puter "rotten" and putere "to stink"), from PIE *pu- (2) "to rot, decay" (source also of Sanskrit puyati "rots, stinks," putih "stinking, foul, rotten;" Greek puon "discharge from a sore," pythein "to cause to rot;" Lithuanian pūvu, pūti "to rot;" Gothic fuls, Old English ful "foul"), perhaps originally echoic of a natural exclamation of disgust.

The formation of pus is called suppuration. A collection of pus within the solid tissues is called an abscess. A suppurating open sore is an ulcer. [Century Dictionary]

"having relation in the formation of pus," 1835, from pyogenesis, medical Latin; see pyo- "pus" + -genic "producing." Related: Pyogenetic (1855); pyogenesis.

"presence of pus in the urine," 1787, from medical Latin (by 1760s), from pyo- + -uria (see urine).