unimpeachably (adverb) unquestionably: without a doubt
Sinonime: absolutely, assuredly,
certainly, decidedly,
definitely,
emphatically, incontrovertibly, indefensibly,
indubitably,
of course,
positively,
surely, undeniably,
undoubtedly, unequivocally, unimpeachably
Antonime: doubtfully, dubiously, questionably