adamant determined dogged headstrong inflexible intractable ornery persistent perverse relentless rigid single-minded steadfast tenacious tough unshakable willful balky bullheaded cantankerous contumacious cussed firm fixed hardheaded inexorable insubordinate mulish obdurate opinionated persevering pertinacious pigheaded rebellious recalcitrant refractory self-willed set in one's ways stiff-necked unbending unmanageable unreasonable untoward