Source : Webster's Revised Unabridged Dictionary (1913)

Dubiously \Du"bi*ous*ly\, adv.
   In a dubious manner.

Source : WordNet®

dubiously
     adv 1: in a questionable and dubious manner; "these were estates
            his father questionably acquired" [syn: {questionably}]
     2: in a doubtful manner; "Gerald shook his head doubtfully"
        [syn: {doubtfully}]