Synonyms and related words :
armed, cloaked, copyrighted, covered, deathless, defended, dependable, fail-safe, firm, guaranteed, guarded, harmless, immortal, impenetrable, imperishable, impregnable, incontestable, incorruptible, indelible, indestructible, indomitable, ineffaceable, ineradicable, inexpugnable, inextinguishable, insuperable, invincible, inviolable, irresistible, nonperishable, overpowering, overwhelming, patented, policed, protected, quenchless, reliable, resistless, riskless, safe, safeguarded, screened, sheltered, shielded, sound, stable, steady, trustworthy, unassailable, unbeatable, unconquerable, undampable, undangerous, undefeatable, undestroyable, undying, unhazardous, unperilous, unprecarious, unquenchable, unrisky, unsubduable, unsurmountable, unyielding, warranteed