(n.) The quality or state of being inflexible, or not capable of being bent or changed; unyielding stiffness; inflexibleness; rigidity; firmness of will or purpose; unbending pertinacity; steadfastness; resoluteness; unchangeableness; obstinacy.

act of God adamantness certainty concentration constancy dourness fate fatefulness firmness firmness of mind fixedness flintiness force majeure fundamentalism grimness hard-bittenness hard-nosedness hardness immobility immobilization immovability immovableness immutability implacability impliability indefeasibility inductility inelasticity ineluctability inertia inescapableness inevasibleness inevitability inevitable accident inevitableness inexorability inextensibility inextricability intractability intransigeance intransigence intransigency intransigentism irreconcilability irremovability irresilience irresiliency irrevocability loyalty necessity obduracy obdurateness obstinacy orthodoxy precisianism predetermination purism puritanism relentlessness rigidity rigidness rigor rigorism rigorousness settledness solidity staunchness steadfastness steadiness steeliness sternness stiff temper stiffness stubbornness sureness toughness trueness unalterability unavoidable casualty unavoidableness unbendingness unchangeability uncompromisingness uncontrollability undeflectability ungivingness unlimberness unmalleability unmovability unpliability unpreventability unrelentingness unyieldingness vis inertiae vis major