Source : Webster's Revised Unabridged Dictionary (1913)

Osteotomy \Os`te*ot"o*my\, n.
   1. The dissection or anatomy of bones; osteology.

   2. (Surg.) The operation of dividing a bone or of cutting a
      piece out of it, -- done to remedy deformity, etc.

Source : WordNet®

osteotomy
     n : surgical sectioning of bone