The Collaborative International Dictionary of English v.0.48:

Propitiate \Pro*pi"ti*ate\, v. t. [imp. & p. p. Propitiated;
   p. pr. & vb. n. Propitiating.] [L. propitiatus, p. p. of
   propitiare to propitiate, fr. propitius favorable. See
   Propitious.]
   To appease to render favorable; to make propitious; to
   conciliate.
   [1913 Webster]

         Let fierce Achilles, dreadful in his rage,
         The god propitiate, and the pest assuage. --Pope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Propitiate \Pro*pi"ti*ate\, v. i.
   To make propitiation; to atone.
   [1913 Webster]

WordNet (r) 3.0 (2006):

propitiate
    v 1: make peace with [syn: propitiate, appease]