Source : Webster's Revised Unabridged Dictionary (1913)

Vasectomy \Vas*ec"to*my\ (v[a^]s*[e^]k"t[-o]*m[y^]), n. [Vas +
   -ecmoty.] (Surg.)
   Resection or excision of the vas deferens.

Source : WordNet®

vasectomy
     n : surgical procedure that removes all or part of the vas
         deferens (usually as a means of sterilization); is
         sometimes reversible