obstinate; stubborn; headstrong
Describes a person who refuses to change their opinion or behavior, often with a negative connotation of inflexibility.
He's stubborn, so once he says something, he won't listen.
あの子は強情で、謝ろうとしない。
That child is obstinate and refuses to apologize.
That child is really stubborn.
He stubbornly insisted on his own opinion.