The Collaborative International Dictionary of English v.0.48:

Chivalry \Chiv"al*ry\, n. [F. chevalerie, fr. chevalier knight,
   OF., horseman. See Chevalier, and cf. Cavalry.]
   1. A body or order of cavaliers or knights serving on
      horseback; illustrious warriors, collectively; cavalry.
      "His Memphian chivalry." --Milton.
      [1913 Webster]

            By his light
            Did all the chivalry of England move,
            To do brave acts.                     --Shak.
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   2. The dignity or system of knighthood; the spirit, usages,
      or manners of knighthood; the practice of knight-errantry.
      --Dryden.
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   3. The qualifications or character of knights, as valor,
      dexterity in arms, courtesy, etc.
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            The glory of our Troy this day doth lie
            On his fair worth and single chivalry. --Shak.
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   4. (Eng. Law) A tenure of lands by knight's service; that is,
      by the condition of a knight's performing service on
      horseback, or of performing some noble or military service
      to his lord.
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   5. Exploit. [Obs.] --Sir P. Sidney.
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   Court of chivalry, a court formerly held before the lord
      high constable and earl marshal of England as judges,
      having cognizance of contracts and other matters relating
      to deeds of arms and war. --Blackstone.
      [1913 Webster]

WordNet (r) 3.0 (2006):

chivalry
    n 1: courtesy towards women [syn: chivalry, gallantry,
         politesse]
    2: the medieval principles governing knighthood and knightly
       conduct [syn: chivalry, knightliness]

Moby Thesaurus II by Grady Ward, 1.0:

100 Moby Thesaurus words for "chivalry":
   Dutch courage, FFVs, ancienne noblesse, aristocracy, arms,
   art of war, baronage, baronetage, bigheartedness, bigness,
   boldness, braveness, bravery, chivalrousness,
   conspicuous gallantry, courage, courageousness, courtesy,
   courtliness, courtly politeness, doughtiness, elect, elevation,
   elite, equitableness, errantry, exaltation, fairness, gallantness,
   gallantry, gallantry under fire, generalship, generosity,
   generousness, great heart, greatheartedness, greatness,
   greatness of heart, haut monde, heroicalness, heroism, high life,
   high society, high-mindedness, honor, idealism, impartiality,
   intrepidity, intrepidness, justness, knight-errantry, knightage,
   knighthood, knightliness, largeheartedness, liberality,
   liberalness, lionheartedness, loftiness, magnanimity,
   magnanimousness, manfulness, manhood, manliness, martial spirit,
   military spirit, nobility, noble-mindedness, nobleness, noblesse,
   noblesse de robe, noblesse oblige, old nobility, openhandedness,
   peerage, politeness, pot-valor, princeliness, prowess,
   righteousness, royalty, soldierly quality, stalwartness,
   stoutheartedness, stoutness, sublimity, the Four Hundred,
   the classes, upper classes, upper crust, upper ten,
   upper ten thousand, uppercut, valiance, valiancy, valor,
   valorousness, virtue, virtuousness, war



Bouvier's Law Dictionary, Revised 6th Ed (1856):

CHIVALRY, ancient Eng. law. This word is derived from the French chevelier,
a horseman. It is. the name of a tenure of land by knight's service.
Chivalry was of two kinds: the first; which was regal, or held only of the
king; or common, which was held of a common person. Co. Litt. h.t.