1 stubborn, intractable.
2 firmly adhering to one's chosen course of action or opinion despite dissuasion.
3 inflexible, self-willed.
4 unyielding; not readily responding to treatment etc.
Derivatives:
obstinacy n. obstinately adv.
Etymology: ME f. L obstinatus past part. of obstinare persist (as OB-, stare stand)
Useful english dictionary. 2012.