hard-shell Synonyms

entrenched rigid relentless refractory invincible inveterate intractable ingrained inexorable ineradicable indomitable settled severe irradicable cussed deep-seated deep-rooted confirmed authoritarian unruly ungovernable strict stern harsh froward contrary conch chronic cantankerous bullheaded bitter austere astringent adamant accustomed contumacious cruel foolhardy flinty fixed firm exacting disobedient disciplinary determined demanding defiant accepted