The Collaborative International Dictionary of English v.0.48:

Circumcision \Cir`cum*cision\, n. [L. circumcisio.]
   1. The act of cutting off the prepuce or foreskin of males,
      or the internal labia of females.
      [1913 Webster]

   Note: The circumcision of males is practiced as a religious
         rite by the Jews, Mohammedans, etc.
         [1913 Webster]

   2. (Script.)
      (a) The Jews, as a circumcised people.
      (b) Rejection of the sins of the flesh; spiritual
          purification, and acceptance of the Christian faith.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Circumcision
    n 1: (Roman Catholic Church and Anglican Church) feast day
         celebrating the circumcision of Jesus; celebrated on
         January 1st [syn: Circumcision, Feast of the
         Circumcision, January 1]
    2: the act of circumcising performed on males eight days after
       birth as a Jewish and Muslim religious rite
    3: the act of circumcising; surgical removal of the foreskin of
       males