Synonyms for Perpetual:

adj.

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

n.

common, immortal, short, imperishable, frequent, sempiternal, never-ceasing, a lot, often, transitory, all the time, frequently, repeatedly, regularly. continue, Eterne, amaranthine, world without end. relentless, ongoing, unfailing, round the clock, around the clock. perpetual (noun)
constant, ageless, continuous, uninterrupted, ceaseless, unremitting, unending, everlasting, endless, incessant, continual, unceasing, permanent, lasting, eternal, never-ending.

Other synonyms:

amaranthine, often, always, repeatedly, regularly, round the clock, around the clock, world without end, frequently. common, Eterne, ongoing. relentless. persistent
never-ceasing.

Usage examples for perpetual

  1. The first method is the most common, since the mountains in Igorot land are full of small, usually perpetual streams. – The Bontoc Igorot by Albert Ernest Jenks
  2. And they sent many ladies and maidens into perpetual captivity. – The White Knight: Tirant lo Blanc by Joanot Martorell and Marti Johan d'Galba
  3. The perpetual secretaries shall be members of the class, but shall make no part of any section. – Paris As It Was and As It Is by Francis W. Blagdon