unyielding Synonyms

dogged tenacious persistent dour pertinacious strict strong strong-minded stubborn sustained taut unshakable unrelenting tireless unmovable tough unbending unbowed uncompromising unflexible unflinching unmerciful stiff-backed retardative rheumatic rigid rigorous ruthless self-willed set single-minded sound stiff-necked stable staunch steadfast steady steely stern stiff resolved unswayable unsubduable nonporous unflagging unswerving unforgiving well-made strong-willed precast