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.