The Collaborative International Dictionary of English v.0.48:

Barbarism \Bar"ba*rism\ (b[aum]r"b[.a]*r[i^]z'm), n. [L.
   barbarismus, Gr. barbarismo`s; cf. F. barbarisme.]
   1. An uncivilized state or condition; rudeness of manners;
      ignorance of arts, learning, and literature;
      barbarousness. --Prescott.
      [1913 Webster]

   2. A barbarous, cruel, or brutal action; an outrage.
      [1913 Webster]

            A heinous barbarism . . . against the honor of
            marriage.                             --Milton.
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   3. An offense against purity of style or language; any form
      of speech contrary to the pure idioms of a particular
      language. See Solecism.
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            The Greeks were the first that branded a foreign
            term in any of their writers with the odious name of
            barbarism.                            --G. Campbell.
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WordNet (r) 3.0 (2006):

barbarism
    n 1: a brutal barbarous savage act [syn: brutality,
         barbarity, barbarism, savagery]

Moby Thesaurus II by Grady Ward, 1.0:

96 Moby Thesaurus words for "barbarism":
   Gothicism, Irish bull, Neanderthalism, age of ignorance, animality,
   antiphrasis, bad taste, barbarity, barbarousness, benightedness,
   benightment, bestiality, bombasticness, brutality, brutishness,
   cacology, cacophony, clumsiness, coarseness, colloquialism,
   corruption, crudeness, cumbrousness, dark, dark age, darkness,
   dysphemism, error, foreignism, gracelessness, grossness, harshness,
   heathenism, heaviness, ill breeding, ill-balanced sentences,
   impoliteness, impropriety, impurity, incivility, inconcinnity,
   incorrectness, indecorousness, inelegance, inelegancy, infelicity,
   lack of finish, lack of polish, lapse, leadenness, localism,
   malaprop, malapropism, misconstruction, missaying, misusage,
   misuse, neologism, paganism, philistinism, pompousness,
   ponderousness, poor diction, roughness, rudeness, savagery,
   savagism, sesquipedalianism, sesquipedality, shibboleth, slang,
   slip, slipshod construction, solecism, spoonerism, stiltedness,
   taboo word, tastelessness, troglodytism, turgidity,
   uncivilizedness, uncouthness, uncultivatedness, uncultivation,
   unculturedness, unenlightenment, uneuphoniousness, ungracefulness,
   ungrammaticism, unrefinement, unseemliness, unwieldiness,
   vernacularism, vulgarism, vulgarity, wildness