1) Believably 2) Belike 3) Credibly 4) I guess 5) I guess so 6) Odds are 7) Perhaps 8) Plausibly 9) Reasonably 1) Belike 2) Doubtless 3) God in fiction 4) In all likelihood 5) In all probability 6) Likely 7) Most likely 8) With considerable certainty 9) Without much doubt 
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• (adv.) In a probable manner; in likelihood.
Prob'a·bly adverb In a probable manner; in likelihood. « Distinguish between what may possibly and what will probably be done.» L'Estrange. 
[adv] - with considerable certainty
probably 1. In all likelihood; very likely. 2. With considerable certainty; without much doubt. 3. Easy to believe on the basis of available evidence.
likely adverb with considerable certainty; without much doubt; `He is probably out of the country`; `in all likelihood we are headed for war`
in all likelihood; very likely: He will probably attend.
[Test terms] with considerable certainty; without much doubt