1) Anxiously 2) Doubtfully 3) Falteringly 4) Hesitantly 5) Irresolutely 6) Unsteadily 1) Apprehensively 2) Cautiously 3) Diffidently 4) Distrustfully 5) Doubtingly 6) Falteringly 7) Hesitantly 8) In an unsteady manner 9) Showing lack of certainty 10) Shyly 11) Suspiciously 12) Tentatively 13) Timidly 14) Undecidedly 15) Unsteadily 
• (adv.) In an uncertain manner.
[adv] - showing lack of certainty
adverb showing lack of certainty; `he paused uncertainly`