cast–iron

1 not allowing for any exceptions or loosening of standards lost weight only after a cast-iron adherence to his diet Synonyms brassbound, cast-iron, exacting, hard-line, inflexible, rigorous, strict, stringent, uncompromisingRelated Words close, conscientious, exact, fussy, meticulous, painstaking, punctilious, scrupulous, undeviating; adamant, adamantine, determined, dogged, firm, relentless, resolved, single-minded, steadfast, stubborn, tenacious, unbending, unflinching; immovable, implacable, unappeasable, unrelenting, unsparing, unyielding; austere, demanding, flinty, grim, hard, hardened, hard-hearted, harsh, ironbound, severe, stern, toughNear Antonyms acquiescent, compliant, compromising, pliable, pliant, relenting, yielding; easy, easygoing, gentle, indulgent, kindly, lenient, merciful, mild, pampering, soft, spoiling, tolerant; neglectful, negligent, remiss, slipshod, sloppy, slovenly, unfussyAntonyms flexible, lax, loose, relaxed, slack

2 able to withstand hardship, strain, or exposure he has a cast-iron faith in his innate ability to overcome any adversity that life might throw against him Synonyms cast-iron, hard, hard-bitten, hardened, inured, rugged, stout, strong, sturdy, tough, toughened, vigorousRelated Words flinty, leathery, resilient, stalwart; durable, enduring, everlasting, immortal, imperishable, lasting, permanent, stable, staunch (also stanch), staying, tenacious, unyielding; flourishing, prospering, thriving; able-bodied, brawny, muscular; fit, fortified, hale, healthy, husky, lusty, red-blooded, robust, sound, strapping, virile; annealed, seasoned, temperedNear Antonyms emasculated, enervated, enfeebled, exhausted, run-down, sapped, wasted, weakened, worn, worn out; crippled, debilitated, diseased, incapacitated, infirm, unsound; fragile, frail, puny; resistless, sensitive, susceptible, unresistant, vulnerable, yielding; mortal, perishable, temporary, transientAntonyms delicate, nonhardy, soft, tender, weak