Source : Webster's Revised Unabridged Dictionary (1913)

Nephrotomy \Ne*phrot"o*my\, n. [Gr. ? a kidney + ? to cut: cf.
   F. n['e]phrotomie.] (Surg.)
   Extraction of stone from the kidney by cutting.

Source : WordNet®

nephrotomy
     n : incision into a kidney (usually to remove a kidney stone)