dubiously
1. [ adverb ] in a questionable and dubious manner
Synonyms: questionably
Examples:

"these were estates his father questionably acquired"

Related terms: doubtful questionable doubtful questionable
2. [ adverb ] in a doubtful manner
Synonyms: doubtfully
Examples:

"Gerald shook his head doubtfully"

Related terms: doubtful doubtful doubtful
Similar spelling:   deviously