di·aph·y·sis 
(dī-ăfĭ-sĭs)
(dī-ăfĭ-sĭs)n. pl. di·aph·y·ses (-sēz′)
Anatomy
Anatomy
The shaft of a long bone.
[Greek diaphusis, spinous process of the tibia, from diaphuesthai, to grow between : dia-, dia- + phuesthai, to grow, middle voice of phuein; see bheuə- in the Appendix of Indo-European roots.]
di′a·physi·al (dī′ə-fĭzē-əl), di·aph′y·seal (dī-ăf′ĭ-sēəl, dī′ə-fĭzē-əl) adj.