The Collaborative International Dictionary of English v.0.48:

Journalism \Jour"nal*ism\, n. [Cf. F. journalisme.]
   [1913 Webster]
   1. The keeping of a journal or diary. [Obs.]
      [1913 Webster]

   2. The periodical collection and publication of current news;
      the business of managing, editing, or writing for,
      journals, newspapers, magazines, broadcasting media such
      as radio or television, or other news media such as
      distribution over the internet; as, political journalism;
      broadcast journalism; print journalism.
      [1913 Webster +PJC]

            Journalism is now truly an estate of the realm.
                                                  --Ed. Rev.
      [1913 Webster]

   3. The branch of knowledge that studies phenomena associated
      with news collection, distribution, and editing; a course
      of study, especially in institutions of higher learning,
      that teaches students how to write, edit, or report news.
      [PJC]

WordNet (r) 3.0 (2006):

journalism
    n 1: newspapers and magazines collectively [syn: journalism,
         news media]
    2: the profession of reporting or photographing or editing news
       stories for one of the media