resolute
If you describe someone as resolute, you approve of them because they are very determined not to change their mind or not to give up a course of action.
FORMAL adj
(=determined)
Voters perceive him as a decisive and resolute international leader...
♦
resolutely adv ADV with v, ADV adj
He resolutely refused to speak English unless forced to..., The United States remains resolutely opposed to this.