Source : Webster's Revised Unabridged Dictionary (1913)

Incertain \In*cer"tain\, n. [Pref. in- not + certain: cf. F.
   incertain, L. incertus. See {Certain}.]
   Uncertain; doubtful; unsteady. -- {In*cer"tain*ly}, adv.

         Very questionable and of uncertain truth. --Sir T.
                                                  Browne.

Source : WordNet®

incertain
     adj : lacking or indicating lack of confidence or assurance;
           "uncertain of his convictions"; "unsure of himself and
           his future"; "moving with uncertain (or unsure) steps";
           "an uncertain smile"; "touched the ornaments with
           uncertain fingers" [syn: {uncertain}, {unsure}] [ant: {certain(p)},
            {certain(p)}]