Source : Webster's Revised Unabridged Dictionary (1913)

Extinguishable \Ex*tin"guish*a*ble\, a.
   Capable of being quenched, destroyed, or suppressed.

Source : WordNet®

extinguishable
     adj : capable of being extinguished or killed; "an extinguishable
           fire"; "hope too is extinguishable" [ant: {inextinguishable}]