From Longman Dictionary of Contemporary Englishbecome hardened (to something)become hardened (to something)USED TO/ACCUSTOMED TOto become used to something shocking because you have seen it many times → hardened
Examples from the Corpus
become hardened (to something)• Once a happy, handsome country boy, Inman has become hardened, cynical, burned out.• Many people become human relations victims over and over again without becoming hardened, insensitive or recluses.• He did not become hardened or accustomed. 