Synonyms and related words :
abiding, adamantine, age-long, aged, ancient, antique, bulky, cartilaginous, changeless, chewy, chronic, cohesive, constant, continuing, coriaceous, dense, dependable, diuturnal, enduring, evergreen, fast, fibrous, firm, fixed, frozen, gristly, hard, hardy, heavy, immobile, immutable, indestructible, intact, intransient, inveterate, inviolate, lasting, leatherlike, leathery, long-lasting, long-lived, long-standing, long-term, longeval, longevous, macrobiotic, massive, of long duration, of long standing, perdurable, perduring, perennial, permanent, perpetual, persistent, persisting, quiescent, reliable, remaining, resistant, rigid, ropy, rugged, sempervirent, sinewy, solid, sound, stable, static, stationary, staying, steadfast, steady, stiff, stout, stringy, strong, stubborn, sturdy, substantial, sustained, tenacious, torpid, tough, tough as leather, unaltered, unchangeable, unchanged, unchanging, unchecked, undestroyed, unfading, unfailing, unshifting, untiring, unvaried, unvarying, unyielding, vigorous, viscid, vital, well-built, well-constructed, well-founded, well-grounded, well-made, wiry