The Collaborative International Dictionary of English v.0.48:

Hyostylic \Hy`o*styl"ic\, a. [Hyo- + Gr. ? a pillar.] (Anat.)
   Having the mandible suspended by the hyomandibular, or upper
   part of the hyoid arch, as in fishes, instead of directly
   articulated with the skull as in mammals; -- said of the
   skull.
   [1913 Webster]