grain, ingrained

[1] grain (n)

• 3(a). A relatively small discrete particulate or crystalline mass: a grain of sand.
• 8. The pattern produced, as in stone, by the arrangement of particulate constituents.
• 12. A state of fine crystallization.
• 13(a). Basic temperament or nature; disposition. (b). An essential quality or characteristic.

[2] ingrained (adj)

• 1. Firmly established; deep-seated: ingrained prejudice; the ingrained habits of a lifetime.
• 2. Worked deeply into the texture or fiber: a carpet disfigured by ingrained dirt.

[3] ingrained (adj)

• (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, planted

[4] ingrain (vt)

• 1. To fix deeply or indelibly, as in the mind: "A system that had been ingrained for generations could not be easily undone by change from the top" Doris Kearns Goodwin.
  

... Am Heritage, WordNet 3.0