The Collaborative International Dictionary of English v.0.48:

Ingrain \In"grain`\, v. t. [imp. & p. p. Ingrained; p. pr. &
   vb. n. Ingraining.] [Written also engrain.]
   [1913 Webster]
   1. To dye with or in grain or kermes.
      [1913 Webster]

   2. To dye in the grain, or before manufacture.
      [1913 Webster]

   3. To work into the natural texture or into the mental or
      moral constitution of; to stain; to saturate; to imbue; to
      infix deeply.
      [1913 Webster]

            Our fields ingrained with blood.      --Daniel.
      [1913 Webster]

            Cruelty and jealousy seem to be ingrained in a man
            who has these vices at all.           --Helps.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ingrained
    adj 1: (used especially of ideas or principles) deeply rooted;
           firmly fixed or held; "deep-rooted prejudice"; "deep-
           seated differences of opinion"; "implanted convictions";
           "ingrained habits of a lifetime"; "a deeply planted need"
           [syn: deep-rooted, deep-seated, implanted,
           ingrained, planted]

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "ingrained":
   basic, chronic, colorfast, confirmed, congenital, constant,
   constitutional, deep-dyed, deep-engraven, deep-fixed,
   deep-grounded, deep-laid, deep-rooted, deep-seated, deep-set,
   deep-settled, double-dyed, dyed-in-the-wool, embedded, embossed,
   engrafted, engraved, entrenched, esoteric, essential, established,
   etched, fadeless, fast, firmly established, fixed, fundamental,
   graven, hereditary, immanent, implanted, implicit, impressed,
   imprinted, inalienable, inborn, inbred, incorrigible, inculcated,
   indelible, indelibly impressed, indwelling, infixed, ingrain,
   ingrown, inherent, inherited, innate, inner, instilled, internal,
   intrinsic, inveterate, inward, inwrought, irreducible,
   irreversible, long-established, native, natural, old-line,
   on a rock, on bedrock, organic, private, resident, rooted, secret,
   set, settled, settled in habit, stabilized, subjective, thorough,
   unalienable, unchallengeable, unfading, unquestionable, vested,
   well-established, well-founded, well-grounded, well-set,
   well-settled