1.
firmly or stubbornly adhering to one's purpose, opinion, etc.; not yielding to argument, persuasion, or entreaty.
2.
characterized by inflexible persistance or an unyielding attitude; inflexibly persisted in or carried out: obstinate advocacy of high tariffs.
3.
not easily controlled or overcome: the obstinate growth of weeds.
4.
not yielding readily to treatment, as a disease.