diaphysis

from WordNet (r) 3.0 (2006)

diaphysis
    n 1: the main (mid) section of a long bone [syn: {diaphysis},
         {shaft}]

from The Collaborative International Dictionary of English v.0.48

Diaphysis \Di*aph"y*sis\, n. [Gr. ? a growing through; dia`
   through + ? to bring forth.]
   1. (Bot.) An abnormal prolongation of the axis of
      inflorescence.
      [1913 Webster]

   2. (Anat.) The shaft, or main part, of a bone, which is first
      ossified.
      [1913 Webster]