Source : Webster's Revised Unabridged Dictionary (1913)

Ascertainable \As`cer*tain"a*ble\, a.
   That may be ascertained. -- {As`cer*tain"a*ble*ness}, n. --
   {As`cer*tain"a*bly}, adv.

Source : WordNet®

ascertainable
     adj : capable of being ascertained or found out; "ascertainable
           facts" [syn: {discoverable}]