Synonyms to unfailing

abiding, age-long, aged, ancient, antique, changeless, chronic, commorant, constant, continuing, continuous, diuturnal, durable, dwelling, enduring, evergreen, firm, fixed, frozen, hardy, immobile, immutable, in residence, indefatigable, intact, intransient, inveterate, inviolate, lasting, living, living in, lodging, long-lasting, long-lived, long-standing, long-term, longeval, longevous, macrobiotic, never-failing, of long duration, of long standing, perdurable, perduring, perennial, permanent, perpetual, persistent, persisting, quiescent, remaining, resident, residentiary, residing, rigid, sempervirent, solid, stable, static, stationary, staying, steadfast, steady, sticking, sustained, torpid, tough, unaltered, unceasing, unchangeable, unchanged, unchanging, unchecked, undestroyed, undying, unfading, unfaltering, unqualified, unquestioning, unremitting, unshifting, unvaried, unvarying, vital, wholehearted, assiduous, advertent, agog, alert, all ears, all eyes, ardent, attentive, aware, careful, concentrated, conscious, diligent, dogged, earnest, elaborate, energetic, f