Fes·ter v. i. [imp. & p. p. Festered p. pr. & vb. n. Festering.]
 1. To generate pus; to become imflamed and suppurate; as, a sore or a wound festers.
 Wounds immedicable
 Rankle, and fester, and gangrene.   --Milton.
    Unkindness may give a wound that shall bleed and smart, but it is treachery that makes it fester.   --South.
    Hatred . . . festered in the hearts of the children of the soil.   --Macaulay.
 2. To be inflamed; to grow virulent, or malignant; to grow in intensity; to rankle.