Definition of: tubercle

(t′bər·kəl, ty′-) noun
1. A small rounded eminence or nodule.
2. Bot. A minute swelling on the roots of leguminous plants, which contains a micro–organism believed to absorb nitrogen from the air for the use of the plant.
3. Pathol. A small granular tumor formed within an organ from morbid or infected matter: in the lungs, the seat of pulmonary consumption.
4. Anat. A small knoblike excrescence, especially on the skin or on a bone. [<L tuberculum, dim. of tuber a swelling]
—tu·ber·cu·loid (t·bûr′kyə·loid, ty-) adjective