more rigid

adamant austere definite exact fixed hard-line harsh inflexible intransigent rigorous solid stern stringent uncompromising unyielding

adamantine bullheaded changeless chiseled dead set determined firm hard incompliant inelastic inexorable invariable locked in obdurate set set in stone single-minded static strait-laced tough nut to crack unalterable unbending unbreakable unchanging undeviating unmoving unpermissive unrelenting

broken easy flexible gentle imprecise indefinite inexact irresolute lenient mild pliant soft tolerant unfixed unreliable willing yielding

bending limber pliable