1. 
[syn: credibly, believably, plausibly, probably]
The Collaborative International Dictionary of English v.0.48:
Credibly \Cred"i*bly\, adv.
   In a manner inducing belief; as, I have been credibly
   informed of the event.
   [1913 Webster]
WordNet (r) 3.0 (2006):
credibly
    adv 1: easy to believe on the basis of available evidence; "he
           talked plausibly before the committee"; "he will probably
           win the election" [syn: credibly, believably,
           plausibly, probably] [ant: implausibly,
           improbably, incredibly, unbelievably]