NOUN (3)

1. a philosopher who believes that universals are real and exist independently of anyone thinking of them;

2. a person who accepts the world as it literally is and deals with it accordingly;

3. a painter who represents the world realistically and not in an idealized or romantic style;

The Collaborative International Dictionary of English v.0.48:

Realist \Re"al*ist\, n. [Cf. F. r['e]aliste.]
   1. (Philos.) One who believes in realism; esp., one who
      maintains that generals, or the terms used to denote the
      genera and species of things, represent real existences,
      and are not mere names, as maintained by the nominalists.
      [1913 Webster]

   2. (Art. & Lit.) An artist or writer who aims at realism in
      his work. See Realism, 2.
      [1913 Webster]

   3. a person who avoids unrealistic or impractical beliefs or
      efforts. Contrasted to idealist or visionary.
      [PJC]

WordNet (r) 3.0 (2006):

realist
    n 1: a philosopher who believes that universals are real and
         exist independently of anyone thinking of them
    2: a person who accepts the world as it literally is and deals
       with it accordingly
    3: a painter who represents the world realistically and not in
       an idealized or romantic style

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "realist":
   Cyrenaic, Eleatic, Epicurean, Marxian, Marxist, Megarian, Stoic,
   animist, animistic, atomistic, commonsense,
   commonsense philosopher, cosmotheistic, dialectical materialist,
   down-to-earth, earthy, eclectic, empirical,
   epistemological realist, eudaemonistic, existential, hardheaded,
   hedonic, hedonist, hedonistic, humanist, humanistic, hylomorphous,
   hylotheistic, idealistic, instrumentalist, materialist,
   materialistic, matter-of-fact, mechanist, mechanistic,
   metaphysical, monistic, natural realist, naturalist, naturalistic,
   nominalist, panlogistical, pantheistic, physicist, positivist,
   positivistic, practical, practical person, practical-minded,
   pragmatic, pragmatist, rational, rationalistic, realistic,
   reasonable, sane, scholastic, scientific, scientistic, secular,
   sensationalistic, sensible, sober-minded, sound, sound-thinking,
   straight-thinking, syncretistic, theistic, transcendentalist,
   transcendentalistic, unideal, unidealistic, unromantic,
   unsentimental, utilitarian, vitalistic, voluntarist, voluntaristic,
   worldly