invincibility (n.)

• authenticity
• dependability
• firmness
• immortality
• impenetrability
• imperishability
• impregnability
• incorruptibility
• indestructibility
• indomitability
• invulnerability
• irresistibility
• predictability
• reliability
• secureness
• security
• solidity
• soundness
• stability
• staunchness
• steadfastness
• steadiness
• substantiality
• trustworthiness
• validity