Synonyms and related words :
abiding, accordant, adamant, age-long, aged, alike, ancient, antique, ardent, assiduous, automatic, balanced, calculable, changeless, chronic, committed, consistent, consonant, constant, continuing, continuous, cool, correspondent, dedicated, deep-rooted, dependable, determined, devoted, diligent, diuturnal, dogged, durable, enduring, equable, equal, even, evergreen, faithful, faithworthy, fast, fiducial, firm, firm as Gibraltar, fixed, flat, flinty, frozen, hardy, homogeneous, immobile, immotile, immotive, immovable, immutable, imperturbable, in equilibrium, inalterable, indefatigable, indomitable, industrious, inexorable, inflexible, insistent, intact, intransient, invariable, inveterate, invincible, inviolate, irremovable, lasting, level, liege, long-lasting, long-lived, long-standing, long-term, longeval, longevous, loyal, macrobiotic, marble-constant, measured, mechanical, methodic, monolithic, never-failing, never-tiring, obdurate, obstinate, of a piece, of long duration, of long standing, ordered, orderly, patient, patient as Job, perdurable, perduring, perennial, permanent, perpetual, perseverant, persevering, persistent, persisting, pertinacious, plodding, plugging, predictable, preoccupied, quiescent, rapt, regular, relentless, reliable, remaining, resolute, resolved, rigid, robotlike, secure, sedulous, sempervirent, set, settled, single-minded, sleepless, slogging, smooth, solid, sot, sound, stable, static, stationary, staunch, staying, steady, steely, stubborn, substantial, sure, surefire, sustained, systematic, tenacious, tested, tireless, torpid, tough, tried, tried and true, TRUE, true-blue, trustworthy, trusty, unabating, unaltered, unbending, unbroken, unchangeable, unchanged, unchanging, unchecked, unconquerable, undaunted, undeflectable, undestroyed, undeviating, undifferentiated, undiscouraged, undiversified, undrooping, unfading, unfailing, unfaltering, unflagging, unflappable, unflinching, uniform, unintermitting, uninterrupted, unmovable, unnodding, unqualified, unquestioning, unrelaxing, unrelenting, unremitting, unruffled, unshakable, unshaken, unshifting, unsleeping, unswerving, untiring, unvaried, unvarying, unwavering, unwearied, unwearying, unwinking, unyielding, utterly attentive, vital, weariless, well-balanced, well-founded, well-grounded, wholehearted, without nerves