Funding for improvement projects has come slowly, allowing resentment to fester.
From the time.com
This feud will continue to fester under the next president, whoever that may be.
From the economist.com
That sort of thing can fester in your head when you don't see people as people.
From the charlotteobserver.com
But Bolivia's bitter disputes over resources, rights and race would still fester.
From the economist.com
But the problems weren't allowed to fester, and now the program is back on track.
From the time.com
Disagreements should be controlled and not permitted to fester during the evening.
From the charlotteobserver.com
Like a cancerous tumor left to fester, the friary degenerated from the inside out.
From the dailyherald.com
Their quarrels and differences, free from the infection of malice, did not fester.
From the denverpost.com
If they try to secede again lets just let em go and fester in their own filth.
From the eatocracy.cnn.com
More examples
A sore that has become inflamed and formed pus
Ripen and generate pus; "her wounds are festering"
(festering) (medicine) the formation of morbific matter in an abscess or a vesicle and the discharge of pus
(festering) pus: a fluid product of inflammation
Uncle Fester, or Fester Addams, is a member of the fictional Addams Family. He was played by Jackie Coogan in the original television series, by Christopher Lloyd in the first two feature films, and by Patrick Thomas in the third, Addams Family Reunion. ...
(Festering) Gangrene is a serious and potentially life-threatening condition that arises when a considerable mass of body tissue dies (necrosis). This may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. ...
To become septic; to become rotten; To worsen, especially due to lack of attention
Quicker than someone else.
To become painfully sore. To be inflamed; to grow virulent, or malignant; to grow in intensity; to rankle.