From BiblePortal Wikipedia

King James Dictionary [1]

Stubborn, a. This word is doubtless formed on the root of stub or stiff, and denotes fixed, firm. But the origin of the latter syllable is not obvious.

1. Unreasonably obstinate inflexibly fixed in opinion not to be moved or persuaded by reasons inflexible as a stubborn son a stubborn mind or soul.

The queen is obstinate--stubborn to justice.

2. Persevering persisting steady constant as stubborn attention. 3. Stiff not flexible as a stubborn bow.

Take a plant of stubborn oak.

4. Hardy firm enduring without complaint as stubborn Stoics. 5. Harsh rough rugged. Little used. 6. Refractory not easily melted or worked as a stubborn ore or metal. 7. Refractory obstinately resisting command, the goad or the whip as a stubborn ass or horse.

Webster's Dictionary [2]

(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.