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
obstinacy, obstinateness, obstinacy, tenacity, cussedness, perseverance, immovability, old school, inflexibility
, obduracy, obduration, dogged resolution, resolution, ruling passion, blind side, self-will, contumacy, perversity, pervicacy, pervicacity, indocility, bigotry, intolerance, dogmatism, opiniatry, opiniativeness, fixed idea, fanaticism, zealotry, infatuation, monomania, opinionatedness opinionativeness, mule, opinionist, opinionatist, opiniator, opinator, stickler, dogmatist, bigot, zealot, enthusiast, fanatic, obstinate, tenacious, stubborn, obdurate, casehardened, inflexible, balky, immovable, unshakable, not to be moved, inert, unchangeable, inexorable, mulish, obstinate as a mule, pig-headed, dogged, sullen, sulky, unmoved, uninfluenced unaffected, willful, self-willed, perverse, resty, restive, restiff, pervicacious, wayward, refractory, unruly, heady, headstrong, entete, contumacious, crossgrained, arbitrary, dogmatic, positive, bigoted, prejudiced, creed- bound, prepossessed, infatuated, stiff-backed, stiff necked, stiff hearted, hard-mouthed, hidebound, unyielding, impervious, impracticable, inpersuasible, unpersuadable, intractable, untractable, incorrigible, deaf to advice, impervious to reason, crotchety, obstinately, non possumus, no surrender, ils n'ont rien appris ne rien oublie.
straightness, rectilinearity, directness, inflexibility
, straight line, right line, direct line, short cut, straight, rectilinear, rectilineal, direct, even, right, true, in a line, unbent, virgate, undeviating, unturned, undistorted, unswerving, straight as an arrow, inflexible, laser-straight, ramrod-straight.
hardness, rigidity, renitence, renitency, inflexibility
, temper, callosity, durity, induration, petrifaction, lapidification, lapidescence, vitrification, ossification, crystallization, stone, pebble, flint, marble, rock, fossil, crag, crystal, quartz, granite, adamant, bone, cartilage, hardware, heart of oak, block, board, deal board, iron, steel, cast iron, decarbonized iron, wrought iron, nail, brick, concrete, cement, hard, rigid, stubborn, stiff, firm, starch, starched, stark, unbending, unlimber, unyielding, inflexible, tense, indurate, indurated, gritty, proof, adamant, adamantine, adamantean, concrete, stony, granitic, calculous, lithic, vitreous, horny, corneous, bony, osseous, ossific, cartilaginous, hard as a rock, stiff as buckram, stiff as a poker, stiff as starch, stiff as as board.