Obstinate means stubbornly refusing to change one's opinion or course of action. It implies a strong resistance to persuasion or reason.
Here are some synonyms for obstinate:
* Stubborn
* Headstrong
* Unyielding
* Perverse
* Inflexible
* Intransigent
* Pigheaded
Example:
"Despite the evidence presented, the witness remained obstinate in his denial of the crime."