Was heißt »unnachgiebig« auf Englisch?

Das Adjektiv unnachgiebig lässt sich wie folgt von Deutsch auf Englisch übersetzen:

Deutsch/Englische Beispielübersetzungen

beharrlich:: persistent
beratungsresistent:: fixed in one's views
brutal:: bestial; brutal; brute; brutish; ruffian; tough; violent
dickköpfig:: obstinate; stubborn
drakonisch:: draconian
eigensinnig:: froward; hardheaded; headstrong; obstinate; opinionated; pig-headed; pigheaded; self-opinionated; stubborn; wayward; wilful; willful
eisern:: iron
gnadenlos:: merciless
halsstarrig:: obstinate; stubborn
hartnäckig:: adamantine; besetting; bulldog; confirmed; do-or-die; dogged; doggedly; insistent; intractable; obstinate; obstinately; persevering; persistent; pertinacious; pertinaciously; refractory; stiff-necked; strongheaded; stubborn; stubbornly; tenacious; tough
konsequent:: consequential; forceful
obstinat:: obstinate
rechthaberisch:: bossily; bossy; dogmatic; dogmatically; know-all; self-opinionated
refraktär:: refractory; resistant
renitent:: recalcitrant; reluctant
standhaft:: steadfast
starrköpfig:: obstinate; stubborn
starrsinnig:: obstinate; stubborn
störrisch:: balky
stur:: obstinate; stubborn
unbarmherzig:: merciless; ruthless
unbeirrbar:: undeviating
unbeirrt:: enduring
unbelehrbar:: inconvincible; stubborn; unconvincible; unteachable
uneinsichtig:: insensible
unerbittlich:: adamant; relentless
unerschütterlich:: unshakeable
verbohrt:: narrow-minded
widerborstig:: rebellious; unruly
widerspenstig:: recalcitrant

Tom is inflexible, isn't he?
Tom is quite inflexible.
You're too inflexible.
Tom is very inflexible.
I'm not inflexible.
Every politician must be responsive to complaints from the public, or he or she will become inflexible and make disastrous decisions.
Tom is inflexible.