undoubtful
adjective
un·doubtful
¦ən+
1
: not open to doubt : firmly established
an undoubtful pedigree
2
: feeling no doubt : confident
a child undoubtful of the stork
W. J. Locke
W. J. Locke
Word History
Etymology
Middle English undouteful, from un- entry 1 + douteful doubtful