Source : Webster's Revised Unabridged Dictionary (1913)

Conquerable \Con*quer*a*ble\, a.
   Capable of being conquered or subdued. --South. --
   {Con"quer*a*ble*ness}, n.

Source : WordNet®

conquerable
     adj 1: subject to being conquered or overcome; "knew her fears were
            ultimately conquerable" [ant: {unconquerable}]
     2: capable of being surmounted or excelled [syn: {superable}]