Philistinism, abstruseness, arduousness, armor, asperity, astringency, austerity, bothersomeness, burdensomeness, callosity, callousness, callus, closeness, cohesiveness, coldbloodedness, coldheartedness, coldness, compactness, complexity, complication, congestedness, congestion, consistence, consistency, crabbedness, crampedness, crowdedness, cruelty, deepness, denseness, density, difficultness, difficulty, durability, esoterica, firmness, flintiness, formidable defenses, fundamentalism, gluiness, grimness, hairiness, hard heart, hard shell, hardenedness, hardheartedness, hardiness, hardness of heart, hardship, harshness, heart of stone, heartlessness, impenetrability, impenitence, impenitentness, impermeability, imperviousness, impliability, imporosity, inclemency, incompressibility, induration, inexorability, inexorableness, inflexibility, infrangibility, insensitiveness, insensitivity, insolence, intricacy, inuredness, irrepentance, jammedness, knottiness, laboriousness, lastingness, leatherlikeness, mercilessness, nonrepentance, obduracy, obdurateness, obstinacy, onerousness, oppressiveness, orthodoxy, pitilessness, precisianism, profoundness, profundity, purism, puritanism, reconditeness, relative density, relentlessness, remorselessness, resistance, rhinoceros hide, rigidity, rigidness, rigor, rigorousness, ropiness, roughness, ruggedness, ruthlessness, seared conscience, severity, short shrift, solidity, solidness, soundness, specific gravity, spissitude, stability, stamina, staunchness, sternness, stiffness, stoniness, stoutness, strength, strenuousness, stringency, stringiness, stubbornness, sturdiness, temper, tenacity, tender mercies, thick skin, thickness, toilsomeness, toughness, troublesomeness, unabjectness, unbendingness, unbreakability, unbreakableness, uncompassionateness, uncompromisingness, uncontriteness, unfeeling, unfeelingness, unforgivingness, ungentleness, unmercifulness, unnaturalness, unrelentingness, unremorsefulness, unresponsiveness, unsympatheticness, unyieldingness, vicissitude, vigor, viscidity, viscosity, viscousness, vitality