festered

/F EH1 S T ER0 D/
verb
  1. 1

    To become septic; to become rotten.

  2. 2

    To worsen, especially due to lack of attention.

    โ€œDeal with the problem immediately; do not let it fester.โ€

  3. 3

    To cause to fester or rankle.

Source: https://en.wiktionary.org/wiki/fester, https://en.wiktionary.org/wiki/festered