The Collaborative International Dictionary of English v.0.48:

Appeasable \Ap*peas"a*ble\, a.
   Capable of being appeased or pacified; placable. --
   Ap*peas"a*ble*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

appeasable
    adj 1: capable of being pacified [syn: appeasable,
           conciliable]