English to English

adverb (r)

• easy to believe on the basis of available evidence(adv.all)

  Synonym:
  believably, plausibly, probably
  Antonym:
  implausibly, improbably, incredibly, unbelievably
  

  source: wordnet30
• In a manner inducing belief; as, I have been credibly informed of the event.(adverb)

  source: webster1913