hardened

adjective

• 1having become or been made hard or harder:hardened steel
• strengthened or made secure against attack, especially by nuclear weapons:the silos are hardened against air attack

• 2 [attributive] very experienced in a particular job or activity and therefore not easily upset by its more unpleasant aspects:hardened police officers [in combination]:a battle-hardened veteran
• utterly fixed in a habit or way of life seen as bad:hardened criminals a hardened liar