metosteon

from The Century Dictionary.

• noun In ornithology, the posterior lateral piece or special ossification of the sternum, behind the pleurosteon, on each side of the lophosteon. See cut under carinate.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Anat.) The postero-lateral ossification in the sternum of birds; also, the part resulting from such ossification.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun anatomy The posterolateral ossification in the sternum of birds.
• noun anatomy The part resulting from such ossification.