(a.) Firm as a stub or stump; stiff; unbending; unyielding; persistent; hence, unreasonably obstinate in will or opinion; not yielding to reason or persuasion; refractory; harsh; -- said of persons and things; as, stubborn wills; stubborn ore; a stubborn oak; as stubborn as a mule.

adamant adamantine adherent adhesive assiduous balking balky bigoted bulldogged bulldoggish bulldoggy bulletheaded bullheaded cantankerous cartilaginous case-hardened chewy clingy cohesive constant continuing contumacious coriaceous determined diligent dogged dogmatic dour durable enduring faithful fanatic fibrous firm fundamentalist gluey glutinous gristly gummy hard hardheaded hardy headstrong hidebound immovable immutable impliable inalterable indefatigable indomitable inductile industrious inelastic inexorable inextensible inextensile inextensional inflexible insistent insubordinate intolerant intractable intractile intransigent invincible iron ironbound ironclad ironhanded irresilient lasting leatherlike leathery loyal mulish muscle-bound never-tiring nonelastic nonstretchable obdurate obstinate opinionated ornery orthodox overzealous patient patient as Job permanent perseverant persevering persistent persisting pertinacious pigheaded plodding plugging preoccupied procrustean purist puristic puritan puritanic rapt rebellious recalcitrant refractory relentless resistant resolute restive rigid rigorist rigoristic rigorous rockbound ropy sedulous self-adhesive self-willed set sinewy single-minded sleepless slogging stable steadfast steady stickable sticky stiff stiff-necked straightlaced straitlaced stringy strong strong-willed strongheaded stunt sulky sullen tacky tenacious tireless tough tough as leather unabating unalterable unbending uncompromising unconquerable uncooperative undaunted undiscouraged undrooping unextendible unextensible unfailing unfaltering unflagging unflexible unflinching ungiving unintermitting uninterrupted unlimber unmalleable unnodding unpliable unpliant unregenerate unrelaxing unrelenting unremitting unsleeping unswerving untiring untractable unwavering unwearied unwearying unwinking unyielding utterly attentive vigorous viscid wayward weariless willful wiry