Definition of unquestionably:
unarguably, right on, really, definitely, sure, aye, easily, uh-huh, inarguably, unimpeachably, alright, all right, forsooth, hands down, emphatically, yep, affirm, in spades, OK, yea, agreed, yeah, gladly, doubtless, truly, so, yes, by all odds, willingly, Roger, decidedly.
certainly (part of speech: adverb)
- beyond doubt,
- without a doubt,
- of course,
- past dispute,
- past a doubt,
- beyond a shadow of a doubt,
- "The Allen House or Twenty Years Ago and Now", T. S. Arthur.
- "Max", Katherine Cecil Thurston.
Yes, unquestionably, said Amy Waring in her mind, which was so cool, so impartial, so merely contemplating the subject as an abstract question, some men- let me see, shall I say like Lawrence Newt, simply as an illustration?- "Trumps", George William Curtis.