obstinate

Synonyms: adamant cantankerous contradictory contrary contumacious convinced dead set on dogged dogmatic firm hard hardened headstrong heady immovable indomitable inflexible intractable intransigent locked in mulish obdurate opinionated opinionative persistent pertinacious perverse pigheaded recalcitrant refractory relentless resolved restive selfwilled steadfast strong-minded tenacious unalterable unflinching unmanageable unyielding willful

Antonyms: agreeable amenable cooperative flexible helpful submissive willing yielding