Source : Webster's Revised Unabridged Dictionary (1913)

Godspeed \God"speed`\, n.
   Success; prosperous journeying; -- a contraction of the
   phrase, ``God speed you.'' [Written also as two separate
   words.]

         Receive him not into house, neither bid him God speed.
                                                  --2 John 10.

Source : WordNet®

Godspeed
     n : a successful journey; "they wished him Godspeed"