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]