Source : Webster's Revised Unabridged Dictionary (1913)

Hyosternal \Hy`o*ster"nal\, a. [Hyo- + ternal.] (Anat.)
      (a) Between the hyoid bone and the sternum, or pertaining
          to them; infrahyoid; as, the hyosternal region of the
          neck.
      (b) Pertaining to the hyosternum of turtles.