fester

Short definition from Wiktionary

Noun

1. 1
   A fistula.
2. 2
   A sore or an ulcer of the skin.
3. 3
   The condition of something that festers; a festering; a festerment.

Verb

1. 1
   To become septic; to become rotten.
2. 2
   To worsen, especially due to lack of attention.
3. 3
   To cause to fester or rankle.

Proper noun

1. 1
   A surname from German.