putrescence n.

late 14c., "festering gangrenous, in a state of decay," from Old French putride and directly from Latin putridus, from putrere "to rot," from putris "rotten, crumbling," related to putere "to stink," from PIE root *pu- (2) "to rot, stink" (see pus). First in reference to putrid fever, an old name for typhus (also known in Middle English as putrida), which supposedly was caused by putrefaction of bodily humors. Related: Putridness.

"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).