The Collaborative International Dictionary of English v.0.48:

Domesticate \Do*mes"ti*cate\, v. t. [imp. & p. p.
   Domesticated; p. pr. & vb. n. Domesticating.] [LL.
   domesticatus, p. p. of domesticare to reside in, to tame. See
   Domestic, a.]
   1. To make domestic; to habituate to home life; as, to
      domesticate one's self.
      [1913 Webster]

   2. To cause to be, as it were, of one's family or country;
      as, to domesticate a foreign custom or word.
      [1913 Webster]

   3. To tame or reclaim from a wild state; as, to domesticate
      wild animals; to domesticate a plant.
      [1913 Webster]

WordNet (r) 3.0 (2006):

domesticate
    v 1: adapt (a wild plant or unclaimed land) to the environment;
         "domesticate oats"; "tame the soil" [syn: domesticate,
         cultivate, naturalize, naturalise, tame]
    2: overcome the wildness of; make docile and tractable; "He
       tames lions for the circus"; "reclaim falcons" [syn:
       domesticate, domesticize, domesticise, reclaim,
       tame]
    3: make fit for cultivation, domestic life, and service to
       humans; "The horse was domesticated a long time ago"; "The
       wolf was tamed and evolved into the house dog" [syn:
       domesticate, tame]