Pertinacious

[ pur-tn-ey-shuhs ]

adjective

  1. holding firmly to an opinion or a course of action.

Examples of pertinacious in a sentence:

  •  The pertinacious girl would not stop trying to sell cookies to the toothless man.
  •  Although Elise has failed her driver’s test six times, her pertinacious spirit will not allow her to stop trying