Synonyms and related words :
authenticity, authoritativeness, calculability, deathlessness, dependability, faithworthiness, firmness, immortality, impenetrability, imperishability, impregnability, incorruptibility, indelibility, indestructibility, indomitability, ineffaceability, ineradicability, inerasableness, inexpugnability, insuperability, inviolability, invulnerability, irresistibility, predictability, reliability, secureness, security, solidity, soundness, stability, staunchness, steadfastness, steadiness, substantiality, trustworthiness, unassailability, unattackableness, unbeatableness, unconquerableness, unerringness, validity