Definition of undoubtedly:
in my humble opinion, hands down, beyond/without a shadow of a doubt, know for a fact (that), correct me if I'm wrong, yep, willingly, forsooth, beyond question, yeah, I bet/I'll bet (that), doubtless, yes, Roger, certain, inarguably, aye, beyond any doubt, without doubt, alright, so, limited, no doubt/question but that, right on, gladly, of course, unless I'm mistaken, really, agreed, truly, sure, affirm, yea, uh-huh, all right, easily, put money on something, OK, unarguably.
- certainly (part of speech: adverb)
- "The Story of the Heavens", Robert Stawell Ball.
- "An Artist in Crime", Rodrigues Ottolengui.
- "Amos Huntingdon", T.P. Wilson.