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.