The Collaborative International Dictionary of English v.0.48:

Rude \Rude\, a. [Compar. Ruder; superl. Rudest.] [F., fr. L.
   rudis.]
   1. Characterized by roughness; umpolished; raw; lacking
      delicacy or refinement; coarse.
      [1913 Webster]

            Such gardening tools as art, yet rude, . . . had
            formed.                               --Milton.
      [1913 Webster]

   2. Hence, specifically:
      (a) Unformed by taste or skill; not nicely finished; not
          smoothed or polished; -- said especially of material
          things; as, rude workmanship. "Rude was the cloth."
          --Chaucer.
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                Rude and unpolished stones.       --Bp.
                                                  Stillingfleet.
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                The heaven-born child
                All meanly wrapt in the rude manger lies.
                                                  --Milton.
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      (b) Of untaught manners; unpolished; of low rank; uncivil;
          clownish; ignorant; raw; unskillful; -- said of
          persons, or of conduct, skill, and the like. "Mine
          ancestors were rude." --Chaucer.
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                He was but rude in the profession of arms. --Sir
                                                  H. Wotton.
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                the rude forefathers of the hamlet sleep.
                                                  --Gray.
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      (c) Violent; tumultuous; boisterous; inclement; harsh;
          severe; -- said of the weather, of storms, and the
          like; as, the rude winter.
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                [Clouds] pushed with winds, rude in their shock.
                                                  --Milton.
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                The rude agitation [of water] breaks it into
                foam.                             --Boyle.
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      (d) Barbarous; fierce; bloody; impetuous; -- said of war,
          conflict, and the like; as, the rude shock of armies.
      (e) Not finished or complete; inelegant; lacking
          chasteness or elegance; not in good taste;
          unsatisfactory in mode of treatment; -- said of
          literature, language, style, and the like. "The rude
          Irish books." --Spenser.
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                Rude am I in my speech.           --Shak.
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                Unblemished by my rude translation. --Dryden.
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   Syn: Impertinent; rough; uneven; shapeless; unfashioned;
        rugged; artless; unpolished; uncouth; inelegant; rustic;
        coarse; vulgar; clownish; raw; unskillful; untaught;
        illiterate; ignorant; uncivil; impolite; saucy;
        impudent; insolent; surly; currish; churlish; brutal;
        uncivilized; barbarous; savage; violent; fierce;
        tumultuous; turbulent; impetuous; boisterous; harsh;
        inclement; severe. See Impertiment.
        [1913 Webster] -- Rude"ly, adv. -- Rude"ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

rudeness
    n 1: a manner that is rude and insulting [syn: discourtesy,
         rudeness] [ant: courtesy, good manners]
    2: a wild or unrefined state [syn: crudeness, crudity,
       primitiveness, primitivism, rudeness]

Moby Thesaurus II by Grady Ward, 1.0:

126 Moby Thesaurus words for "rudeness":
   Gothicism, bad manners, bad taste, barbarism, barbarousness,
   bombasticness, brashness, brassiness, brazenfacedness, brazenness,
   cacology, cacophony, caddishness, callowness, cheekiness,
   clumsiness, coarseness, cockiness, contempt, cracked voice,
   crassness, crudeness, crudity, cumbrousness, derision, discord,
   discourteousness, discourtesy, disrespectfulness, dryness,
   dysphemism, earthiness, face of brass, flippancy, freshness,
   gaudiness, gracelessness, greenness, gross behavior, grossness,
   gruffness, gutturalism, gutturality, gutturalness, harshness,
   heaviness, hoarseness, huskiness, ill breeding, ill manners,
   ill-balanced sentences, immatureness, immaturity, impertinence,
   impoliteness, impropriety, impudence, impurity, incivility,
   inconcinnity, inconsiderateness, incorrectness, indecorousness,
   inelegance, inelegancy, infelicity, insensitivity, inurbanity,
   lack of finish, lack of polish, leadenness, loudness, loutishness,
   mannerlessness, meretriciousness, nondevelopment, obscenity,
   offensiveness, oversimplicity, oversimplification, pompousness,
   ponderousness, poor diction, raspiness, raucity, rawness,
   reductionism, ribaldry, ridicule, roughness, scrapiness,
   scratchiness, sesquipedalianism, sesquipedality, simplism,
   slipshod construction, stertorousness, stiltedness, tactlessness,
   tastelessness, the rough, thickness, throatiness, turgidity,
   ugliness, uncourtliness, uncouthness, uncultivation, undevelopment,
   uneuphoniousness, unfinish, unfinishedness, unfledgedness,
   ungallantness, ungentlemanliness, ungracefulness, ungraciousness,
   unmannerliness, unpoliteness, unrefinement, unripeness,
   unseemliness, unsolicitousness, unwieldiness, vulgarism,
   vulgarity



Bouvier's Law Dictionary, Revised 6th Ed (1856):

RUDENESS, crim. law. An impolite action; contrary to the usual rules
observed in society, committed by one person against another.
     2. This is a relative term which it is difficult to define: those acts
which one friend might do to another, could not be justified by persons
altogether unacquainted persons moving in polished society could not be
permitted to do to each other, what boatmen, hostlers, and such persons
might perhaps justify. 2 Hagg. Eccl. R. 73. An act done by a gentleman
towards a lady might be considered rudeness, which, if done by one gentleman
to another might not be looked upon in that light. Russ. & Ry. 130.
     3. A person who touches another with rudeness is guilty of a battery.
(q.v.)