adjective

lasting forever or a very long time.

the damned would suffer everlasting torment

eternal,never-ending,endless,without end,perpetual,undying,immortal,deathless,indestructible,immutable,abiding,enduring,infinite,boundless,timeless,sempiternal,perdurable,constant,continual,continuous,persistent,sustained,unremitting,relentless,unrelenting,unrelieved,uninterrupted,unbroken,unabating,interminable,non-stop,round-the-clock,incessant,ceaseless

noun

eternity.