Doubtfully

Doubt′ful-ly

,

adv.

In a doubtful manner.

Nor did the goddess

doubtfully

declare.

Dryden.

, adv.

1.

In a doubtful manner; dubiously.

2.

With doubt; irresolutely.

3.

Ambiguously; with uncertainty of meaning.

Nor did the goddess doubtfully declare.

4.

In a state of dread.

doubtfully ‎(comparative more doubtfully, superlative most doubtfully)

In a doubtful manner, in context of doubt or ambiguity, questionably.
- 1920, Herman Cyril McNeile, Bulldog Drummond Chapter 1
  He looked at the mauve envelope doubtfully, and examined the postmark. "Where is Pudlington, James? and one might almost ask—why is Pudlington? No town has any right to such an offensive name."

doubtful manner