1. to become infected and produce pus
Usage: medical
2. to become worse or more intense over time, especially negative emotions or problems
Usage: figurative

Examples

• The wound began to fester after several days without proper care.
• If you don’t clean that cut, it will fester and become infected.
• His anger continued to fester long after the argument ended.
• The dispute was allowed to fester until it became a major crisis.
• Resentment can fester in relationships when issues aren’t addressed.
• The political tensions festered throughout the summer.
• Don’t let small problems fester into bigger ones.