adverb (r)

• in a stupid manner(adv.all)

  Synonym:
  densely, doltishly, obtusely, stupidly
  

  source: wordnet30
• in an inarticulate manner(adv.all)

  Example:
  I nodded dumbly and he slit the envelope.
  

  Synonym:
  inarticulately
  

  source: wordnet30
• In silence; mutely.(adverb)

  source: webster1913