undoubtable

/ʌnˈdaʊtəbəl/
adjective
  1. Not able to be doubted; certain or unquestionable.
    • Her talent as a musician is undoubtable after that perfect performance.
    • The evidence presented in court was undoubtable and convinced the jury.
    • His loyalty to the team is undoubtable; he has never missed a practice.