The Collaborative International Dictionary of English v.0.48:

Tubercle \Tu"ber*cle\, n. [L. tuberculum, dim. of tuber: cf. F.
   tubercule, OF. also tubercle. See Tuber.]
   [1913 Webster]
   1. A small knoblike prominence or excrescence, whether
      natural or morbid; as, a tubercle on a plant; a tubercle
      on a bone; the tubercles appearing on the body in leprosy.
      [1913 Webster]

   2. (Med.) A small mass or aggregation of morbid matter;
      especially, the deposit which accompanies scrofula or
      phthisis. This is composed of a hard, grayish, or
      yellowish, translucent or opaque matter, which gradually
      softens, and excites suppuration in its vicinity. It is
      most frequently found in the lungs, causing consumption.
      [1913 Webster]

   Tubercle bacillus (Med.), a minute vegetable organism
      (Mycobacterium tuberculosis, formerly Bacillus
      tuberculosis, and also called Koch's bacillus)
      discovered by Koch, a German physician, in the sputum of
      consumptive patients and in tuberculous tissue. It is the
      causative agent of tuberculosis.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

tubercle
    n 1: a swelling that is the characteristic lesion of
         tuberculosis
    2: small rounded wartlike protuberance on a plant [syn:
       nodule, tubercle]
    3: a protuberance on a bone especially for attachment of a
       muscle or ligament [syn: tuberosity, tubercle,
       eminence]

Moby Thesaurus II by Grady Ward, 1.0:

121 Moby Thesaurus words for "tubercle":
   abscess, aposteme, bed sore, bilge, blain, bleb, blister, blob,
   boil, boss, bow, bubble, bubo, bulb, bulbil, bulge, bulla, bump,
   bunch, bunion, burl, button, cahot, canker, canker sore, carbuncle,
   chancre, chancroid, chilblain, chine, clump, cold sore, condyle,
   convex, corm, dowel, ear, eschar, felon, fester, festering,
   fever blister, fistula, flange, flap, furuncle, furunculus, gall,
   gathering, gnarl, gumboil, handle, hemorrhoids, hill, hump, hunch,
   jog, joggle, kibe, knob, knot, knur, knurl, lesion, lip, loop,
   lump, mole, mountain, nevus, nub, nubbin, nubble, papilloma,
   papula, papule, paronychia, parulis, peg, petechia, piles, pimple,
   pock, polyp, pustule, radicle, radix, rhizome, rib, ridge, ring,
   rising, root, rootstock, scab, shoulder, soft chancre, sore, spine,
   stigma, stud, sty, style, suppuration, swelling, tab, tap, taproot,
   tuber, tubercule, ulcer, ulceration, verruca, vesicle, wale, wart,
   welt, wheal, whelk, whitlow, wound