bull-headed

/B UH1 L EH0 D AH0 D/
adjective
  1. 1

    Unreasonably stubborn.

    โ€œJohn was so bullheaded that he kept driving and refused to stop for directions, even after getting hopelessly lost.โ€

Source: https://en.wiktionary.org/wiki/bull-headed, https://en.wiktionary.org/wiki/bullheaded