rock-ribbed Synonyms

rockbound unrelenting unbending tenacious stubborn stiff-necked stiff steely steadfast staunch stalwart uncompromising undaunted stubborn as a mule strong-willed unswerving unflagging die hard unwavering dead set unyielding unshakable spirited rocky rigid inexorable indefatigable immovable firm dogged determined craggy contrarious brave inflexible insistent intransigent resolute relentless pertinacious persistent persevering pebbly obstinate obdurate lapidarian adamant