Source : Webster's Revised Unabridged Dictionary (1913)

Credibly \Cred"i*bly\, adv.
   In a manner inducing belief; as, I have been credibly
   informed of the event.

Source : WordNet®

credibly
     adv : easy to believe on the basis of available evidence; "he
           talked plausibly before the committee"; "he will
           probably win the election" [syn: {believably}, {plausibly},
            {probably}] [ant: {incredibly}]