putrid (adj.)

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]

c. 1400, putrefaccioun, "process of decomposition of organic matter," from Old French putrefaction (14c.), from Latin putrefactionem (nominative putrefactio), noun of action from past-participle stem of putrefacere "to make rotten," from putrere "to be rotten" (see putrid) + facere "to make, do" (from PIE root *dhe- "to set, put"). By early 15c. as "that which is putrid or decomposed." Putrification sometimes also is used. Related: Putrefactive.