The Collaborative International Dictionary of English v.0.48:

Civilize \Civ"i*lize\, v. t. [imp. & p. p. Civilized; p. pr. &
   vb. n. Civilizing.] [Cf. F. civilizer, fr.L. civilis civil.
   See Civil.]
   1. To reclaim from a savage state; to instruct in the rules
      and customs of civilization; to educate; to refine.
      [1913 Webster]

            Yet blest that fate which did his arms dispose
            Her land to civilize, as to subdue.   --Dryden
      [1913 Webster]

   2. To admit as suitable to a civilized state. [Obs. or R.]
      "Civilizing adultery." --Milton.

   Syn: To polish; refine; humanize.
        [1913 Webster]

WordNet (r) 3.0 (2006):

civilize
    v 1: teach or refine to be discriminative in taste or judgment;
         "Cultivate your musical taste"; "Train your tastebuds";
         "She is well schooled in poetry" [syn: educate, school,
         train, cultivate, civilize, civilise]
    2: raise from a barbaric to a civilized state; "The wild child
       found wandering in the forest was gradually civilized" [syn:
       civilize, civilise]

Moby Thesaurus II by Grady Ward, 1.0:

66 Moby Thesaurus words for "civilize":
   acculturate, advance, ameliorate, amend, anthropomorphize, better,
   boost, bring forward, broaden, broaden the mind, catechize,
   demonstrate, direct, domesticate, edify, educate, elevate, emend,
   enhance, enlighten, enrich, fatten, favor, forward, foster,
   give instruction, give lessons in, go straight, ground, guide,
   humanize, illumine, improve, improve upon, inform, instruct, lard,
   lift, make an improvement, make human, meliorate, mend, nurture,
   open the eyes, polish, promote, raise, reeducate, refine,
   refine upon, reform, school, set right, sharpen the wits, show,
   show how, socialize, straighten out, tame, teach, teach a lesson,
   teach the rudiments, transfigure, transform, upgrade, uplift