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.

late 14c., putrefien, "to decompose, rot, decay with a fetid smell," from Old French putréfier and directly from Latin putrefacere "to make rotten," from putrere "to stink" (see putrid) + facere "to make, do" (from PIE root *dhe- "to set, put"). Transitive sense of "cause to decompose or rot" is from early 15c. Related: Putrefied; putrefying.

"a putrid state; tendency to decay," 1640s, from Latin putrescentem (nominative putrescens), present participle of putrescere "grow rotten, molder, decay," inchoative of putrere "be rotten" (see putrid). Related: Putrescency.

"becoming or growing putrid or rotten," 1732, a back-formation from putrescence, or else from Latin putrescentem (nominative putrescens), present participle of putrescere "grow rotten, molder, decay," inchoative of putrere "be rotten" (see putrid).

"corruption, rottenness, putrid matter," 1630s, from Medieval Latin putriditas, from Latin putridus (see putrid). In this sense Middle English had putrede (c. 1400).