The Collaborative International Dictionary of English v.0.48:

Lithotrity \Li*thot"ri*ty\, n. [Litho- + L. terere, tritum, to
   rub, grind.] (Surg.)
   The operation of breaking a stone in the bladder or urethrea
   into small pieces capable of being voided; lithotripsy.
   [1913 Webster]