The Collaborative International Dictionary of English v.0.48:

Materialist \Ma*te"ri*al*ist\ (m[.a]*t[=e]"r[i^]*al*[i^]st), n.
   [Cf. F. mat['e]rialiste.]
   1. One who denies the existence of spiritual substances or
      agents, and maintains that spiritual phenomena, so called,
      are the result of some peculiar organization of matter. A
      believer in philosophical materialism.
      [1913 Webster +PJC]

   2. One who holds to the existence of matter, as distinguished
      from the idealist, who denies it. --Berkeley.
      [1913 Webster] Materialistic

WordNet (r) 3.0 (2006):

materialist
    n 1: someone with great regard for material possessions
    2: someone who thinks that nothing exists but physical matter