The Collaborative International Dictionary of English v.0.48:

Persuadable \Per*suad"a*ble\, a.
   That may be persuaded. -- Per*suad"a*ble*ness, n. --
   Per*suad"a*bly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

persuadable
    adj 1: being susceptible to persuasion [syn: convincible,
           persuadable, persuasible, suasible]