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]