The Collaborative International Dictionary of English v.0.48:

Celebrate \Cel"e*brate\, v. t. [imp. & p. p. Celebrated; p.
   pr. & vb. n. Celebrating.] [L. celebratus, p. p. of
   celebrare to frequent, to celebrate, fr. celeber famous.]
   1. To extol or honor in a solemn manner; as, to celebrate the
      name of the Most High.
      [1913 Webster]

   2. To honor by solemn rites, by ceremonies of joy and
      respect, or by refraining from ordinary business; to
      observe duly; to keep; as, to celebrate a birthday.
      [1913 Webster]

            From even unto even shall ye celebrate your Sabbath.
                                                  --Lev. xxiii.
                                                  32.
      [1913 Webster]

   3. To perform or participate in, as a sacrament or solemn
      rite; to solemnize; to perform with appropriate rites; as,
      to celebrate a marriage.

   Syn: To commemorate; distinguish; honor.

   Usage: To Celebrate, Commemorate. We commemorate events
          which we desire to keep in remembrance, when we recall
          them by some special observace; as, to commemorate the
          death of our Savior. We celebrate by demonstrations of
          joy or solemnity or by appropriate ceremonies; as, to
          celebrate the birthday of our Independence.
          [1913 Webster]

                We are called upon to commemorate a revolution
                as surprising in its manner as happy in its
                consequences.                     --Atterbury.
          [1913 Webster]

                Earth, water, air, and fire, with feeling glee,
                Exult to celebrate thy festival.  --Thomson.
          [1913 Webster]

WordNet (r) 3.0 (2006):

celebrate
    v 1: behave as expected during of holidays or rites; "Keep the
         commandments"; "celebrate Christmas"; "Observe Yom Kippur"
         [syn: observe, celebrate, keep]
    2: have a celebration; "They were feting the patriarch of the
       family"; "After the exam, the students were celebrating"
       [syn: celebrate, fete]
    3: assign great social importance to; "The film director was
       celebrated all over Hollywood"; "The tenor was lionized in
       Vienna" [syn: lionize, lionise, celebrate]

Moby Thesaurus II by Grady Ward, 1.0:

116 Moby Thesaurus words for "celebrate":
   administer Communion, adulate, advertise, apotheosize,
   attend Communion, attend Mass, beat the drum, belaud, bepraise,
   blare, blare forth, blaze, blaze abroad, blazon, blazon about,
   bless, bless the Lord, blow the trumpet, blow up, boast of,
   brag about, broadcast, carouse, celebrate Mass, commemorate,
   communicate, consecrate, conventionalize, cry, cry out, cry up,
   cut loose, debauch, declaim, dedicate, deify, dignify, doxologize,
   dress ship, emblazon, eulogize, exalt, extol, fire a salute,
   flatter, formalize, glorify, glorify the Lord, hallow, hell around,
   herald, herald abroad, hero-worship, hold, hold jubilee, honor,
   hymn, idolize, jollify, jolly, jubilate, jubilize, keep, lark,
   laud, let go, let loose, let off steam, lionize, maffick, magnify,
   make merry, make much of, make whoopee, mark, memorialize, observe,
   overpraise, panegyrize, party, pay tribute, perform,
   porter aux nues, praise, praise God, proclaim, promulgate,
   publicize, puff, puff up, raise hell, receive the Sacrament,
   rejoice in, revel, ritualize, roister, salute, sanctify, see life,
   shout, signalize, sing praises, skylark, solemnize, solemnly mark,
   sound a fanfare, spree, step out, stylize, thunder, thunder forth,
   trumpet, trumpet forth, wanton, wassail, whoop it up