Synonyms for Everlasting:

adj.

abiding (adjective)
enduring, steady, persistent.
continuing (adjective)
unending.
continuous (adjective)
interminable, repeated, undying, monotonous, unchanging, perennial, endless, steady, ceaseless, cyclical, sequential, undeviating, continual, consistent, repetitive, seamless, un-intermittent, unremitting, straight, flat, featureless, gapless, unceasing, even, level, indefatigable, habitual, regular, unbroken, constant, invariable, homogeneous, consecutive, incessant, perpetual, monolithic, unchangeable, continuous, connected, uniform, unvarying, lasting, coherent, robot-like, continuing, persistent, nonstop, recurrent, unending.
durable (adjective)
lifelong, lifetime, eternal, long-life, durable, interminable, prolonged, long, lengthy, livelong, perennial, perpetual, incessant, enduring, lasting.
infinite (adjective)
ceaseless, immeasurable, endless, incalculable, immemorial, unbounded, inexhaustible, numberless, interminable, innumerable, bottomless, countless, eternal, Termless, timeless, limitless, infinite, unlimited, boundless, perpetual, illimitable.
infinite, never-ending (adjective)
boundless, ceaseless, lasting, constant, abiding, continual, unceasing, Termless, permanent, limitless, continuous, incessant, uninterrupted, endless, immortal, amaranthine, unremitting, perpetual, unending, interminable, eternal, timeless, undying.
never-ending (adjective)
undying, ceaseless.
permanent (adjective)
constant, permanent, enduring, unchangeable, persistent, fixed, abiding, immutable, lasting, perpetual.
perpetual (adjective)
uninterrupted, permanent, constant, enduring, immortal, interminable, endless, infinite, ceaseless, continual, unceasing, eternal, lasting, incessant.

n.

extended, long-term, for some time, on and on. continue, indefinite, amaranthine, Eterne, world without end, forever. lingering, day in day out, relentless, round the clock, ongoing, around the clock, long-drawn-out, protracted. everlasting (noun)
endless, eternal, perpetual, infinite, constant, relentless, interminable, incessant, continuous, immortal, undying, unremitting, persistent, permanent, timeless.

Other synonyms:

lingering, long-drawn-out, protracted, around the clock, round the clock, amaranthine, world without end. forever, Eterne, ongoing. relentless. Other relevant words:
ongoing, extended, forever, indefinite, protracted, lingering, amaranthine, Eterne, relentless, long-term, continue, long-drawn-out, round the clock.

Usage examples for everlasting

  1. God's mercy is from everlasting to everlasting – Love's Final Victory by Horatio
  2. I wonder you do not think yourselves immortal in those everlasting gardens! – The Portland Sketch Book by Various
  3. While I have everlasting faith in our Republic, it would be folly, indeed, to blind ourselves to our problems at home. – Complete State of the Union Addresses from 1790 to the Present by Various