Source : Webster's Revised Unabridged Dictionary (1913)

Knight-errant \Knight"-er`rant\, n.; pl. {Knight-errants}, or
   {Knights-errant}.
   A wandering knight; a knight who traveled in search of
   adventures, for the purpose of exhibiting military skill,
   prowess, and generosity.

Source : WordNet®

knight-errant
     n : a wandering knight travelling in search of adventure