Lewis & Short

fūruncŭlus, i, m. dim. [fur], a petty thief, pilferer (cf. furax).

  1. I. Lit.: olim furunculus, nunc etiam rapax, Cic. Pis. 27, 66; Tert. adv. Marc. 3, 16.
  2. II. Transf.
    1. A. A pointed, burning sore on the human body, a boil, furuncle, Cels. 5, 28, 8; Plin. 20, 13, 50, § 130.
    2. B. A germ or knob on a vine, so called from its shape, Col. 4, 22, 4; 4, 24, 5; Plin. 17, 22, 36, § 181.