The Collaborative International Dictionary of English v.0.48:

Appease \Ap*pease"\, v. t. [imp. & p. p. Appealed; p. pr. &
   vb. n. Appeasing.] [OE. apesen, apaisen, OF. apaisier,
   apaissier, F. apaiser, fr. a (L. ad) + OF. pais peace, F.
   paix, fr. L. pax, pacis. See Peace.]
   To make quiet; to calm; to reduce to a state of peace; to
   still; to pacify; to dispel (anger or hatred); as, to appease
   the tumult of the ocean, or of the passions; to appease
   hunger or thirst.
   [1913 Webster]

   Syn: To pacify; quiet; conciliate; propitiate; assuage;
        compose; calm; allay; hush; soothe; tranquilize.
        [1913 Webster]

WordNet (r) 3.0 (2006):

appease
    v 1: cause to be more favorably inclined; gain the good will of;
         "She managed to mollify the angry customer" [syn: pacify,
         lenify, conciliate, assuage, appease, mollify,
         placate, gentle, gruntle]
    2: overcome or allay; "quell my hunger" [syn: quell, stay,
       appease]
    3: make peace with [syn: propitiate, appease]