The Collaborative International Dictionary of English v.0.48:

Materialism \Ma*te"ri*al*ism\, n. [Cf. F. mat['e]rialisme.]
   1. The doctrine of materialists; materialistic views and
      tenets; called also philosophical materialism.
      [1913 Webster]

            The irregular fears of a future state had been
            supplanted by the materialism of Epicurus.
                                                  --Buckminster.
      [1913 Webster]

   2. The tendency to give undue importance to material
      interests as contrasted with spiritual concerns; devotion
      to the material nature and its wants.
      [1913 Webster]

   3. Material substances in the aggregate; matter. [R. & Obs.]
      --A. Chalmers.
      [1913 Webster]

   philosophical materialism The theory that matter and energy
      are the only objects existing within the universe, and
      that mental and spiritual phenomena are explainable as
      functions of the nervous system of people. Same as
      materialism[1].
      [PJC]

WordNet (r) 3.0 (2006):

materialism
    n 1: a desire for wealth and material possessions with little
         interest in ethical or spiritual matters [syn:
         materialism, philistinism]
    2: (philosophy) the philosophical theory that matter is the only
       reality [syn: materialism, physicalism]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "materialism":
   Adam, Marxism, Philistinism, animalism, animality, atomism,
   beastliness, behaviorism, bestiality, brutality, brutishness,
   carnal nature, carnal-mindedness, carnality, coarseness,
   commonsense realism, dialectical materialism, earthiness,
   earthliness, earthly-mindedness, empiricism, epiphenomenalism,
   fallen nature, fallen state, flesh, fleshliness, grossness,
   historical materialism, hylomorphism, hylotheism, hylozoism,
   idealism, lapsed state, mechanism, mundaneness, natural realism,
   naturalism, new realism, nonspirituality, physicalism, physicism,
   positive philosophy, positivism, postlapsarian state, pragmaticism,
   pragmatism, realism, representative realism, secularism,
   substantialism, swinishness, temporality, the Old Adam, the beast,
   the flesh, the offending Adam, unspirituality, worldliness,
   worldly-mindedness