Synonyms for Probably:

adv.

likely to happen (adverb)
one can assume, imaginably, feasibly, apparently, possibly, no doubt, presumably, practicably, reasonably, believably, as the case may be, in all likelihood, expediently, most likely, like enough, plausibly, in all probability.
probably (adverb)
likely, aptly, possibly, plausibly, presumably.

adv

probably (adverb)
likely, aptly, possibly, plausibly, presumably.
supposedly (adverb)
believably.

n.

expected, good, bound, guaranteed, probable, sure, certain. presumably (noun)
practicably, imaginably, everything being equal, to all appearance, as the case may be, one can assume, mingly, no doubt, feasibly, most likely, as like as not, like enough, reasonably, apparently, expediently.
probably (noun)
credibly, in all likelihood, believably, in all probability, likely, plausibly, belike.

Other synonyms:

expected. guaranteed, probable. certain. bound. sure. good. Other relevant words:
credibly, apparently, as the case may be, belike, guaranteed, expediently, no doubt, reasonably, feasibly, in all probability, bound, one can assume, like enough, believably, most likely, in all likelihood, practicably, imaginably, certain, good, probable.