The Collaborative International Dictionary of English v.0.48:

Accustom \Ac*cus"tom\, v. t. [imp. & p. p. Accustomed; p. pr.
   & vb. n. Accustoming.] [OF. acostumer, acustumer, F.
   accoutumer; [`a] (L. ad) + OF. costume, F. coutume, custom.
   See Custom.]
   To make familiar by use; to habituate, familiarize, or inure;
   -- with to.
   [1913 Webster]

         I shall always fear that he who accustoms himself to
         fraud in little things, wants only opportunity to
         practice it in greater.                  --Adventurer.
   [1913 Webster]

   Syn: To habituate; inure; exercise; train.
        [1913 Webster]