The Collaborative International Dictionary of English v.0.48:

Errantry \Er"rant*ry\, n.
   1. A wandering; a roving; esp., a roving in quest of
      adventures. --Addison.
      [1913 Webster]

   2. The employment of a knight-errant. --Johnson.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "errantry":
   Wanderjahr, aberrancy, aberration, afoot and lighthearted, bend,
   bias, bigheartedness, bigness, branching off, bumming,
   chivalrousness, chivalry, circuitousness, corner, crook, curve,
   declination, departure, detour, deviance, deviancy, deviation,
   deviousness, digression, discursion, divagation, divarication,
   divergence, diversion, dogleg, double, drift, drifting, elevation,
   exaltation, excursion, excursus, exorbitation, flitting, gadding,
   generosity, generousness, great heart, greatheartedness, greatness,
   greatness of heart, hairpin, heroism, high-mindedness, hoboism,
   idealism, indirection, itineracy, itinerancy, knight-errantry,
   knightliness, largeheartedness, liberality, liberalness, loftiness,
   magnanimity, magnanimousness, nobility, noble-mindedness,
   nobleness, nomadism, obliquity, openhandedness, peregrination,
   pererration, princeliness, ramble, rambling, roam, roaming, rove,
   roving, sheer, shift, shifting, shifting course, shifting path,
   skew, slant, straying, sublimity, sweep, swerve, swerving,
   swinging, tack, traipsing, turn, turning, twist, vagabondage,
   vagabondia, vagabondism, vagrancy, variation, veer, wandering,
   wanderlust, warp, wayfaring, yaw, zigzag