Synonyms and related words :
deathless, enduring, eternal, everlasting, immortal, imperishable, impregnable, incorruptible, indelible, indestructible, ineffaceable, ineradicable, inexpugnable, invincible, invulnerable, irrefragable, irrepressible, nonperishable, quenchless, undampable, undestroyable, undying, unquenchable