English to English

adverb (r)

• in a grave and sober manner(adv.all)

  Synonym:
  soberly, staidly
  

  source: wordnet30
• to a severe or serious degree(adv.all)

  Example:
  Is gravely ill.
  

  Synonym:
  badly, seriously, severely
  

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

  source: webster1913