unyielding Synonyms

pertinacious dogged tenacious dour persistent stiff-backed stiff-necked stiff stern steely steady stony strict strong strong-minded stubborn unconquerable uncompromising unbowed unbending true-blue tough tireless taut sustained sturdy steadfast staunch rheumatic retardative resolved resolute relentless resistive resistant resisting renitent rigid rigorous ruthless stark stable sound solid sisyphean single-minded severe set self-willed remorseless