unyielding russian
упо́рство
persistence, unyieldingness, obstinacy, stubborness, pertinacity, doggedness
непода́тливый
tenacious, inflexible, unyielding, stubborn, unmanageable, hard-mouthed
ерши́стый
bristling, sticking up, obstinate, unyielding
неусту́пчивый
obstinate, uncompromising, unyielding