1. 
[syn: unsteadily, falteringly, uncertainly]
2.  showing lack of certainty; 
- Example: "he paused uncertainly"
The Collaborative International Dictionary of English v.0.48:
Uncertainly \Un*cer"tain*ly\, adv.
   In an uncertain manner.
   [1913 Webster]
WordNet (r) 3.0 (2006):
uncertainly
    adv 1: in an unsteady manner; "he walked unsteadily toward the
           exit"; "The wounded soldier was swinging unsteadily on
           his legs" [syn: unsteadily, falteringly,
           uncertainly] [ant: steadily, steady]
    2: showing lack of certainty; "he paused uncertainly"