Synonyms and related words :
abiding, assiduous, calculable, certain, changeless, consistent, constant, continuing, dependable, devoted, diligent, dogged, durable, enduring, faithful, faithworthy, fast, firm, fixed, frozen, immobile, immutable, inalterable, indefatigable, indomitable, industrious, insistent, intact, invariable, invincible, inviolate, lasting, loyal, marble-constant, never-tiring, obstinate, patient, patient as Job, permanent, perpetual, perseverant, persevering, persistent, persisting, pertinacious, plodding, plugging, predictable, preoccupied, quiescent, rapt, relentless, reliable, remaining, resolute, rigid, secure, sedulous, single-minded, sleepless, slogging, solid, sound, stable, static, stationary, staunch, staying, steadfast, steady, stubborn, substantial, sure, surefire, sustained, tenacious, tireless, torpid, TRUE, true-blue, trustworthy, trusty, unabating, unaltered, unchangeable, unchanged, unchanging, unchecked, unconquerable, undaunted, undestroyed, undiscouraged, undrooping, unfading, unfaltering, unflagging, unflinching, unintermitting, uninterrupted, unnodding, unrelaxing, unrelenting, unremitting, unshifting, unsleeping, unswerving, untiring, unvaried, unvarying, unwavering, unwearied, unwearying, unwinking, utterly attentive, weariless, well-founded, well-grounded