fester UK /ˈfɛstə/US /ˈfɛstɚ/noun 3verb 3forms 4 noun3 •A sore or an ulcer of the skin.He has been away so long and so often, there has been such mismanagement under a long minority, such changes and such misrule, such a hard hand and such a high hand, that the whole place is a fester. — 1864 •The condition of something that festers; a festering; a festerment. •(no longer used) A fistula. verb3 •To become septic; to become rotten.[W]ounds immedicable / Ranckle, and fester, and gangrene, / To black mortification. — 1671 •To cause to fester or rankle.For which I burnt in inward sweltring hate, / And festred rankling malice in my breast, / Till I might belke revenge upon his eyes: […] — 1599 •(figurative) To worsen, especially due to lack of attention.Deal with the problem immediately; do not let it fester. formsfestered · festering · festereth · festers