The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

furuncle
    n 1: a painful sore with a hard core filled with pus [syn:
         boil, furuncle]