Suppurate
Part of speech: verb
Definition: To form or discharge pus.
Fester
Part of speech: verb
Definition: To become septic; to become rotten.To worsen, especially due to lack of attention.
Example sentence: Zionism was originally a rebellion against religious Judaism and the PLO Charter was essentially secularist. But because the conflict was allowed to fester without a resolution, religion got sucked into the escalating cycle of violence and became part of the problem.