Source : Webster's Revised Unabridged Dictionary (1913)

Assignable \As*sign"a*ble\, a.
   Capable of being assigned, allotted, specified, or
   designated; as, an assignable note or bill; an assignable
   reason; an assignable quantity.

Source : WordNet®

assignable
     adj : legally transferable to the ownership of another;
           "negotiable bonds" [syn: {conveyable}, {negotiable}, {transferable},
            {transferrable}]