Source : Webster's Revised Unabridged Dictionary (1913)

Diffidently \Dif"fi*dent*ly\, adv.
   In a diffident manner.

         To stand diffidently against each other with their
         thoughts in battle array.                --Hobbes.

Source : WordNet®

diffidently
     adv : in a diffident manner; "`Oh, well,' he shrugged diffidently,
           `I like the work.'"