adverb (r)

• unmistakably (`plain' is often used informally for `plainly')(adv.all)

  Example:
  He was manifestly too important to leave off the guest list.
  

  Synonym:
  apparently, evidently, obviously, patently, plain, plainly
  

  source: wordnet30
• In a manifest manner.(adverb)

  source: webster1913