WordNet (r) 3.0 (2006):

knight errantry
    n 1: quixotic (romantic and impractical) behavior [syn: knight
         errantry, quixotism]
    2: (Middle Ages) the code of conduct observed by a knight errant
       who is wandering in search of deeds of chivalry

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "knight errantry":
   bigheartedness, bigness, chivalrousness, chivalry, elevation,
   errantry, exaltation, generosity, generousness, great heart,
   greatheartedness, greatness, greatness of heart, heroism,
   high-mindedness, idealism, knightliness, largeheartedness,
   liberality, liberalness, loftiness, magnanimity, magnanimousness,
   nobility, noble-mindedness, nobleness, openhandedness,
   princeliness, sublimity