Synonyms of inflexible

1 Syllable

set, hard, firm, stiff, straight, staunch, mule, tough, strict, stern, nar, tight

2 Syllables

willful, stony, steely, straightest, toughest, lithic, forced, tightest, stubborn, starchier, balkier, steadfast, unbent, hang-tough, bullhead, petrous, stauncher, straighter, seton, mulish, balky, harder, skintight, flinty, sterner, stonier, rightist, staunchest, rocky, stringent, fixed, rockier, hardshell, hard-line, hardest, die-hard, tougher, starchy, rigid, iron, ruber, pebbly, rockbound, short-fuse, callous, sternest, dogged, tighter

3 Syllables

hard-hearted, stiff-necked, rigorous, uniform, racialist, relentless, unswayable, undaring, austere, uncurled, severest, adamant, severer, tenacious, hard-and-fast, ironclad, hard-boiled, hard-nosed, hard-shelled, unbending, hard-bitten, ruffianly, uncompliant, unyielding, hard-handed, hidebound, pigheaded, bouldered, rock-ribbed, collinear, worked-up, strong-minded

4 Syllables

unindulgent, implacable, unrelenting, unshakable, resolute, inductile, contumacious, determined, immovable, rectilineal, singleminded, immutable, invariable, obdurate, doctrinaire, iron-handed, close-fitting, unforgetful, never-failing, case-hardened, intractable, inelastic, dyed-in-the-wool, intransigent, narrowminded, unchangeable, intolerant, closed-minded, single-minded, obstinate, unbendable, lapidarian, stonelike, unrelaxed, xenophobic, chauvinistic

5 Syllables

unpreventable, inexorable, casehardened, inextensible, unadaptable, unpermissive, undiversified, unmodifiable, inevitable, indomitable, traditionalist, isolationist, negativistic, unalterable, uncompromising, adamantine, unreconstructed, conservative, opinionated

6 Syllables

irreconcilable, opinionative, perseverative, traditionalistic