The Collaborative International Dictionary of English v.0.48:

Empiricism \Em*pir"i*cism\, n.
   1. The method or practice of an empiric; pursuit of knowledge
      by observation and experiment.
      [1913 Webster]

   2. Specifically, a practice of medicine founded on mere
      experience, without the aid of science or a knowledge of
      principles; ignorant and unscientific practice;
      charlatanry; quackery.
      [1913 Webster]

   3. (Metaph.) The philosophical theory which attributes the
      origin of all our knowledge to experience.
      [1913 Webster]

WordNet (r) 3.0 (2006):

empiricism
    n 1: (philosophy) the doctrine that knowledge derives from
         experience [syn: empiricism, empiricist philosophy,
         sensationalism]
    2: the application of empirical methods in any art or science
    3: medical practice and advice based on observation and
       experience in ignorance of scientific findings [syn:
       quackery, empiricism]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "empiricism":
   Christian ethics, Marxism, R and D, Stoicism, altruistic ethics,
   animalism, aretaics, atomism, behaviorism, casuistry,
   categorical imperative, commonsense realism, comparative ethics,
   control, control experiment, controlled experiment, cut and try,
   deontology, dialectical materialism, earthliness, egoistic ethics,
   epiphenomenalism, ethical formalism, ethical philosophy, ethology,
   ethonomics, eudaemonics, evolutionism, experiment,
   experimental design, experimental method, experimental proof,
   experimentalism, experimentation, golden rule, hedonism,
   historical materialism, hit and miss, hylomorphism, hylotheism,
   hylozoism, intuitionism, materialism, mechanism, moral philosophy,
   natural realism, naturalism, new realism, noble experiment,
   perfectionism, physicalism, physicism, positive philosophy,
   positivism, pragmaticism, pragmatism, realism,
   representative realism, research and development, rule of thumb,
   secularism, situation ethics, substantialism, temporality,
   tentative method, tentativeness, testing, trial, trial and error,
   trying, utilitarianism, worldliness