Synonyms to heart of stone

armor, Philistinism, aegis, armament, armature, armor plate, bard, beaver, body armor, brassard, breastplate, buckler, bulletproof vest, callosity, callousness, callus, chain armor, chain mail, chitin, cloak, coat of mail, coif, corselet, cortex, cover, cuirass, elytron, episperm, flintiness, formidable defenses, gas mask, gauntlet, guard, habergeon, hard heart, hard shell, hardenedness, hardheartedness, hardness, hardness of heart, harness, hauberk, headpiece, helm, helmet, imperviousness, induration, insensitiveness, insensitivity, inuredness, jamb, lorica, lorication, mail, mantle, nasal, needles, obduracy, obdurateness, panoply, pericarp, plate, plate armor, protection, protective covering, rhinoceros hide, rondel, safeguard, screen, scute, scutum, security, shell, shelter, shield, shroud, spines, stoniness, suit of armor, test, testa, thick skin, veil, visor, ward, analgesia, anesthesia, coldbloodedness, coldheartedness, coldness, deadness, density, dullness, durity, electronarcosis