Metasternum \Met`a*ster"num\, n. [Pref. meta- + sternum.] 1. (Anat.) The most posterior element of the sternum; the ensiform process; xiphisternum. [1913 Webster] 2. (Zool.) The ventral plate of the third or last segment of the thorax of insects. [1913 Webster] Metastoma
Xiphisternum \Xiph"i*ster"num\, n.; pl. {Xiphisterna}. [NL., fr. Gr. xi`fos a sword + sternum.] (Anat.) (a) The posterior segment, or extremity, of the sternum; -- sometimes called {metasternum}, {ensiform cartilage}, {ensiform process}, or {xiphoid process}. (b) The xiphiplastron. -- {Xiph"i*ster"nal}a. [1913 Webster]