Source : Webster's Revised Unabridged Dictionary (1913)

Furuncle \Fu"run*cle\, n. [L. furunculus a petty thief, a boil,
   dim. of fur thief: cf. F. furoncle.] (Med.)
   A superficial, inflammatory tumor, suppurating with a central
   core; a boil.

Source : WordNet®

furuncle
     n : a painful sore with a hard pus-filled core [syn: {boil}]