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

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "circumcision":
   adoption, agape, asperges, aspersion, auricular confession,
   bar mitzvah, bas mitzvah, celebration, confession, confirmation,
   conversion, high celebration, incense, invocation,
   invocation of saints, kiss of peace, lesser litany, litany,
   love feast, lustration, new birth, new life, pax, processional,
   rebirth, reciting the rosary, redeemedness, redemption,
   reformation, regeneration, salvation, second birth,
   spiritual purification, telling of beads, the confessional,
   the confessionary



Easton's 1897 Bible Dictionary:

Circumcision
   cutting around. This rite, practised before, as some think, by
   divers races, was appointed by God to be the special badge of
   his chosen people, an abiding sign of their consecration to him.
   It was established as a national ordinance (Gen. 17:10, 11). In
   compliance with the divine command, Abraham, though ninety-nine
   years of age, was circumcised on the same day with Ishmael, who
   was thirteen years old (17:24-27). Slaves, whether home-born or
   purchased, were circumcised (17:12, 13); and all foreigners must
   have their males circumcised before they could enjoy the
   privileges of Jewish citizenship (Ex. 12:48). During the journey
   through the wilderness, the practice of circumcision fell into
   disuse, but was resumed by the command of Joshua before they
   entered the Promised Land (Josh. 5:2-9). It was observed always
   afterwards among the tribes of israel, although it is not
   expressly mentioned from the time of the settlement in Canaan
   till the time of Christ, about 1,450 years. The Jews prided
   themselves in the possession of this covenant distinction (Judg.
   14:3; 15:18; 1 Sam. 14:6; 17:26; 2 Sam. 1:20; Ezek. 31:18).

     As a rite of the church it ceased when the New Testament times
   began (Gal. 6:15; Col. 3:11). Some Jewish Christians sought to
   impose it, however, on the Gentile converts; but this the
   apostles resolutely resisted (Acts 15:1; Gal. 6:12). Our Lord
   was circumcised, for it "became him to fulfil all
   righteousness," as of the seed of Abraham, according to the
   flesh; and Paul "took and circumcised" Timothy (Acts 16:3), to
   avoid giving offence to the Jews. It would render Timothy's
   labours more acceptable to the Jews. But Paul would by no means
   consent to the demand that Titus should be circumcised (Gal.
   2:3-5). The great point for which he contended was the free
   admission of uncircumcised Gentiles into the church. He
   contended successfully in behalf of Titus, even in Jerusalem.

     In the Old Testament a spiritual idea is attached to
   circumcision. It was the symbol of purity (Isa. 52:1). We read
   of uncircumcised lips (Ex. 6:12, 30), ears (Jer. 6:10), hearts
   (Lev. 26:41). The fruit of a tree that is unclean is spoken of
   as uncircumcised (Lev. 19:23).

     It was a sign and seal of the covenant of grace as well as of
   the national covenant between God and the Hebrews. (1.) It
   sealed the promises made to Abraham, which related to the
   commonwealth of Israel, national promises. (2.) But the promises
   made to Abraham included the promise of redemption (Gal. 3:14),
   a promise which has come upon us. The covenant with Abraham was
   a dispensation or a specific form of the covenant of grace, and
   circumcision was a sign and seal of that covenant. It had a
   spiritual meaning. It signified purification of the heart,
   inward circumcision effected by the Spirit (Deut. 10:16; 30:6;
   Ezek. 44:7; Acts 7:51; Rom. 2:28; Col. 2:11). Circumcision as a
   symbol shadowing forth sanctification by the Holy Spirit has now
   given way to the symbol of baptism (q.v.). But the truth
   embodied in both ordinances is ever the same, the removal of
   sin, the sanctifying effects of grace in the heart.

     Under the Jewish dispensation, church and state were
   identical. No one could be a member of the one without also
   being a member of the other. Circumcision was a sign and seal of
   membership in both. Every circumcised person bore thereby
   evidence that he was one of the chosen people, a member of the
   church of God as it then existed, and consequently also a member
   of the Jewish commonwealth.