The Collaborative International Dictionary of English v.0.48:

autotroph \autotroph\ n.
   an organism which is autotrophic, i. e., an organism (such
   as most plants and certain microorganisms) which are capable
   of synthesizing its own food from simple organic substances,
   requiring only minerals as nutrients for growth, and using
   carbonate or carbon dioxide as a source of carbon and simple
   inorganic nitrogen as a nitrogen source; the energy required
   is derived from photosynthesis or chemosynthesis. Opposed to
   heterotroph. See also auxotroph.

   Syn: autophyte, autophytic plant, autotrophic organism.
        [WordNet 1.5 + PJC]

WordNet (r) 3.0 (2006):

autotroph
    n 1: plant capable of synthesizing its own food from simple
         organic substances [syn: autophyte, autophytic plant,
         autotroph, autotrophic organism]