rigidity

harshness rigor

acerbity austerity cruelty grimness hardheartedness hardness rigorousness sharpness sternness strictness stringency toughness unkindness

gentility kindness mildness

bullheadedness contumacy doggedness grimness indomitability inexorability inexorableness inflexibility inflexibleness intransigence intransigency mulishness obduracy obstinacy perseverance pertinacity pigheadedness relentlessness rigidness

adamancy die-hardism implacability implacableness incompliance incompliancy obdurateness remorselessness