Synonyms and related words :
Philistinism, armor, callosity, callousness, callus, flintiness, formidable defenses, hard heart, hard shell, hardenedness, hardheartedness, hardness, hardness of heart, heart of stone, imperviousness, insensitiveness, insensitivity, inuredness, obduracy, obdurateness, rhinoceros hide, stoniness, thick skin