Source : Webster's Revised Unabridged Dictionary (1913)

Knowable \Know"a*ble\, a.
   That may be known; capable of being discovered, understood,
   or ascertained.

         Thus mind and matter, as known or knowable, are only
         two different series of phenomena or qualities. --Sir
                                                  W. Hamilton.

Source : WordNet®

knowable
     adj : capable of being known [syn: {cognizable}, {cognisable}, {cognoscible}]
           [ant: {unknowable}]