| impenetrable(adjective, unaffected, unyielding, safety, unbending) |
| safe(adjective, secure, harm, perfect, unaffected) |
| impregnable(adjective, strong, secure, resolute, safe) |
| invincible(adjective, strong, resolute, unassailable, untouchable) |
| secure(adjective, safe, intact, unbroken, protected) |
| unbeatable(adjective, invincible) |
| firm |
| immune(adjective, safe, unaffected, unyielding, unbending) |
| protected(adjective, secure, perfect, safe, unaffected) |
| unassailable(adjective, strong, sound, secure, resolute) |
| unconquerable(adjective, insurmountable) |
| indestructible(adjective, invincible) |
| untouchable(adjective, invincible) |
| indomitable(adjective, steadfast, unyielding) |
| inviolable(adjective, secure, perfect, safe, snug) |
| strong(adjective, resolute, unaffected, permanent, resilient) |
| impervious(adjective, secure, safe, unaffected, unyielding) |
| all-conquering |
| defensible(adjective, safety) |
| tight(adjective, close, strong, unaffected, snug) |