The Collaborative International Dictionary of English v.0.48:

Appeasement \Ap*pease"ment\, n.
   The act of appeasing, or the state of being appeased;
   pacification. --Hayward.
   [1913 Webster]

WordNet (r) 3.0 (2006):

appeasement
    n 1: the act of appeasing (as by acceding to the demands of)
         [syn: appeasement, calming]

Moby Thesaurus II by Grady Ward, 1.0:

84 Moby Thesaurus words for "appeasement":
   Eisenhower Doctrine, Monroe Doctrine, Nixon Doctrine,
   Truman Doctrine, United Nations troops, abatement, allayment,
   alleviation, analgesia, anesthesia, anesthetizing, assuagement,
   atonement, balance of power, brinkmanship, calming, coexistence,
   colonialism, compromise, conciliation, containment, deadening,
   detente, deterrence, diminishment, diminution, diplomacy,
   diplomatic, diplomatics, dollar diplomacy, dollar imperialism,
   dulcification, dulling, ease, easement, easing,
   easing of relations, expansionism, foreign affairs, foreign policy,
   good-neighbor policy, imperialism, internationalism, isolationism,
   lessening, lulling, manifest destiny, mediation, militarism,
   mitigation, mollification, nationalism, neocolonialism, neutralism,
   nonresistance, numbing, open door, open-door policy, pacification,
   palliation, peace offensive, peace-keeping force,
   peaceful coexistence, peacemaking, peacemongering, placability,
   placation, preparedness, propitiation, reduction,
   relaxation of tension, relief, remedy, salving,
   shirt-sleeve diplomacy, shuttle diplomacy, softening, soothing,
   spheres of influence, subduement, the big stick, tough policy,
   tranquilization, world politics