putrefy

Short definition from Wiktionary

Verb

1. 1
   To fester or rot and exude a fetid stench.
2. 2
   To become filled with a pus-like or bile-like substance.
3. 3
   To reach an advanced stage of decomposition.
4. 4
   To become gangrenous.
5. 5
   To make morbid, carious, or gangrenous.
6. 6
   To corrupt; to make foul.