The Collaborative International Dictionary of English v.0.48:

Hypidiomorphic \Hy*pid`i*o*mor"phic\, a. [Pref. hypo- +
   idiomorphic.] (Crystallog.)
   Partly idiomorphic; -- said of rock a portion only of whose
   constituents have a distinct crystalline form. --
   Hy*pid`i*o*mor"phic*al*ly, adv.
   [1913 Webster]