The Collaborative International Dictionary of English v.0.48:

Vulgarize \Vul"gar*ize\, v. t. & i. [imp. & p. p. Vulgarized;
   p. pr. & vb. n. Vulgarizing.] [Cf. F. vulgariser, LL.
   vulgarizare.]
   To make vulgar, or common.
   [1913 Webster]

         Exhortation vulgarized by low wit.       --V. Knox.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vulgarize
    v 1: cater to popular taste to make popular and present to the
         general public; bring into general or common use; "They
         popularized coffee in Washington State"; "Relativity Theory
         was vulgarized by these authors" [syn: popularize,
         popularise, vulgarize, vulgarise, generalize,
         generalise]
    2: debase and make vulgar; "The Press has vulgarized Love and
       Marriage" [syn: vulgarise, vulgarize]
    3: act in a vulgar manner; "The drunkard tends to vulgarize"
       [syn: vulgarize, vulgarise]

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "vulgarize":
   adulterate, alloy, canker, cheapen, clarify, coarsen, confound,
   contaminate, corrupt, debase, debauch, defile, deflower,
   degenerate, degrade, denature, deprave, desecrate, despoil,
   devalue, distort, elucidate, explain, explicate, get across,
   get over, infect, make clear, make it clear, misuse, pervert,
   poison, pollute, popularize, prostitute, put across, put over,
   ravage, ravish, simplify, spell out, taint, twist, ulcerate,
   violate, vitiate, warp