(a.) Not admitting of compromise; making no truce or concessions; obstinate; unyielding; inflexible.

adamant adamantine cast-iron dour firm flinty fundamentalist grim hard hard-core hard-line hidebound immovable immutable implacable impliable inelastic inexorable inflexible intransigent iron ironbound ironclad ironhanded irreconcilable muscle-bound obdurate obstinate orthodox procrustean purist puristic puritan puritanic relentless rigid rigorist rigoristic rigorous rock-ribbed rockbound single-minded steely stern stiff straightlaced straitlaced stubborn unaffected unalterable unbending unchangeable uncompliant ungiving unmoved unrelenting unyielding