dumbly

from WordNet (r) 3.0 (2006)

dumbly
    adv 1: in a stupid manner; "he had so rapaciously desired and so
           obtusely expected to find her alone" [syn: {dumbly},
           {densely}, {obtusely}]
    2: in an inarticulate manner; "I nodded dumbly and he slit the
       envelope"

from The Collaborative International Dictionary of English v.0.48

Dumbly \Dumb"ly\, adv.
   In silence; mutely.
   [1913 Webster]