The Oxford Thesaurus An A-Z Dictionary of Synonyms - festerv.

1) ulcerate, suppurate, run, ooze, putrefy, putresce, necrose, mortify, rot, decay, decompose: His entire body was covered with festering sores. 2) rankle, smoulder, gall, chafe, inflame: Bitterness over the way he had been treated festered inside him for years.