inflexible

adamant immutable intractable obstinate resolute rigid rigorous steadfast strict stringent uncompromising unyielding

adamantine determined dogged dyed-in-the-wool firm fixed hang-tough hard hard-and-fast immovable implacable indomitable inexorable iron obdurate relentless set set in one's ways single-minded stand one's ground staunch steely stiff unadaptable unbending unchangeable uncompliant unrelenting unswayable

amenable cooperative easygoing flexible irresolute lenient pliant soft submissive tolerant willing yielding

bendable elastic pliable reasonable resilient

rigid

hard immalleable impliable inelastic nonflexible set starched taut unbending

bendable elastic flexible pliable pliant reasonable resilient soft willing yielding