Source : Webster's Revised Unabridged Dictionary (1913)

Soiree \Soi`ree"\, n. [F., fr. soir evening, fr. L. serus late,
   serum late time. Cf. {Serenade}.]
   An evening party; -- distinguished from levee, and
   matin['e]e.

Source : WordNet®

soiree
     n : a party of people assembled in the evening (usually at a
         private house)