Synonyms and related words :
deathless, defended, guarded, immortal, impenetrable, imperishable, incontestable, incorruptible, indelible, indestructible, indomitable, ineffaceable, ineradicable, inexpugnable, inextinguishable, insuperable, invincible, inviolable, invulnerable, irresistible, mighty, nonperishable, overpowering, overwhelming, protected, quenchless, resistless, safe, safeguarded, secure, shielded, unassailable, unbeatable, unconquerable, undampable, undefeatable, undestroyable, undying, unquenchable, unsubduable, unsurmountable, unyielding