c.1412, from L. putridus, from putrere "to rot," from putris "rotten, crumbling," related to putere "to stink," from PIE base *pu- "to rot, stink" (see pus). First in ref. to putrid fever, an old name for typhus.
You can't help but snarl your upper lip a bit when you say a word like putrid.
What really struck me in the etymology was the PIE base *pu- "to rot, stink". As a parent, it immediately brought to mind the word many folks use to describe such deposits left by infants in their diapers...