sternum

noun

1. the flat bone that articulates with the clavicles and the first seven pairs of ribs

   noun.body

   Synonyms breastbone

   Source: WordNet 3.0

2. 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.

   noun

   Source: webster1913