The Collaborative International Dictionary of English v.0.48:

Sensationalism \Sen*sa"tion*al*ism\, n.
   1. (Metaph.) The doctrine held by Condillac, and by some
      ascribed to Locke, that our ideas originate solely in
      sensation, and consist of sensations transformed;
      sensualism; -- opposed to intuitionalism, and
      rationalism.
      [1913 Webster]

   2. The practice or methods of sensational writing or
      speaking; as, the sensationalism of a novel.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sensationalism
    n 1: subject matter that is calculated to excite and please
         vulgar tastes
    2: the journalistic use of subject matter that appeals to vulgar
       tastes; "the tabloids relied on sensationalism to maintain
       their circulation" [syn: sensationalism, luridness]
    3: (philosophy) the ethical doctrine that feeling is the only
       criterion for what is good [syn: sensualism,
       sensationalism]
    4: (philosophy) the doctrine that knowledge derives from
       experience [syn: empiricism, empiricist philosophy,
       sensationalism]

Moby Thesaurus II by Grady Ward, 1.0:

148 Moby Thesaurus words for "sensationalism":
   Barnumism, Thespian art, affectation, aggrandizement,
   amateur theatricals, amplification, ballyhoo, bedizenment,
   big talk, blatancy, blood and thunder, blowing up, brazenness,
   burlesque, caricature, colorfulness, convolution, crudeness, dash,
   dazzle, dazzlingness, demonstrativeness, dilatation, dilation,
   dramatic art, dramatic form, dramatic irony, dramatic stroke,
   dramatic structure, dramaticism, dramatics, dramatism, dramaturgy,
   emotional appeal, emotionalism, emotionality, emotionalization,
   emotionalizing, emotiveness, emotivity, enhancement, enlargement,
   exaggerating, exaggeration, excess, exorbitance, expansion,
   extravagance, extravaganza, extravagation, extreme, flagrancy,
   flamboyance, flashiness, flatulence, flatulency, fulsomeness,
   gaiety, garishness, gaudery, gaudiness, glare, glitter,
   gorgeousness, grandiloquence, grandioseness, grandiosity,
   heightening, high-flown diction, histrionics, histrionism,
   huckstering, human interest, hyperbole, hyperbolism, inflatedness,
   inflation, inordinacy, jauntiness, jazziness, lexiphanicism,
   loftiness, loudness, love interest, luridness, magnification,
   magniloquence, making scenes, melodrama, melodramatics,
   mere rhetoric, meretriciousness, nonrationalness, obtrusiveness,
   orotundity, ostentation, ostentatious complexity, overemphasis,
   overestimation, overkill, overstatement, panache,
   platitudinous ponderosity, play construction,
   polysyllabic profundity, pomposity, pompous prolixity, pompousness,
   pontification, pretension, pretentiousness, prodigality,
   profuseness, prose run mad, puffery, puffing up, rhetoric,
   rhetoricalness, sententiousness, shamelessness, showiness,
   sportiness, staginess, stiltedness, stretching, superlative,
   swelling utterance, swollen phrase, swollenness, tall talk,
   tawdriness, theatricalism, theatricality, theatricals, theatricism,
   theatrics, tortuosity, tortuousness, touting, travesty, tumidity,
   tumidness, turgescence, turgidity, unreasoningness, visceralness,
   vulgarness, yellow journalism