\Ster"num\, n.; pl. L. {Sterna}, E. {Sternums}. [NL.,
from Gr. ?, the breast, chest.]
1. (Anat.) A plate of cartilage, or a series of bony or
   cartilaginous plates or segments, in the median line of
   the pectoral skeleton of most vertebrates above fishes;
   the breastbone.
Note: The sternum is connected with the ribs or the pectorial
      girdle, or with both. In man it is a flat bone, broad
      anteriorly, narrowed behind, and connected with the
      clavicles and the cartilages of the seven anterior
      pairs of ribs. In most birds it has a high median keel
      for the attachment of the muscles of the wings.
2. (Zo["o]l.) The ventral part of any one of the somites of
   an arthropod.