Source : Webster's Revised Unabridged Dictionary (1913)

Christen \Chris"ten\, v. t. [imp. & p. p. {Christened}; p. pr. &
   vb. n. {Christening}.] [AS. cristnian to make a Christian,
   fr. cristen a Christian.]
   1. To baptize and give a Christian name to.

   2. To give a name; to denominate. ``Christen the thing what
      you will.'' --Bp. Burnet.

   3. To Christianize. [Obs.] --Jer. Taylor.

   4. To use for the first time. [Colloq.]

Source : WordNet®

christening
     n : giving a Christian name at baptism