The Collaborative International Dictionary of English v.0.48:

Loyalty \Loy"al*ty\, n. [Cf. F. loyaut['e]. See Loyal, and cf.
   Legality.]
   The state or quality of being loyal; fidelity to a superior,
   or to duty, love, etc.
   [1913 Webster]

         He had such loyalty to the king as the law required.
                                                  --Clarendon.
   [1913 Webster]

         Not withstanding all the subtle bait
         With which those Amazons his love still craved,
         To his one love his loyalty he saved.    --Spenser.
   [1913 Webster]

   Note: "Loyalty . . . expresses, properly, that fidelity which
         one owes according to law, and does not necessarily
         include that attachment to the royal person, which,
         happily, we in England have been able further to throw
         into the word." --Trench.

   Syn: Allegiance; fealty. See Allegiance.
        [1913 Webster]

WordNet (r) 3.0 (2006):

loyalty
    n 1: the quality of being loyal [syn: loyalty, trueness]
         [ant: disloyalty]
    2: feelings of allegiance
    3: the act of binding yourself (intellectually or emotionally)
       to a course of action; "his long commitment to public
       service"; "they felt no loyalty to a losing team" [syn:
       commitment, allegiance, loyalty, dedication]

Moby Thesaurus II by Grady Ward, 1.0:

146 Moby Thesaurus words for "loyalty":
   abandon, acquiescence, adherence, adhesion, allegiance,
   application, ardency, ardor, assiduity, assiduousness,
   assigned task, attachment, bona fides, bond, bonne foi,
   bounden duty, bulldog tenacity, burden, business, call of duty,
   charge, commitment, committedness, compliance, concentration,
   conformity, constancy, dedication, deference, dependability,
   devoir, devotedness, devotion, devoutness, diligence,
   dogged perseverance, doggedness, duteousness,
   duties and responsibilities, dutifulness, duty, earnestness,
   endurance, engrossment, ethics, faith, faithfulness, fealty,
   fervency, fervidness, fervor, fidelity, fire, firmness,
   firmness of mind, fixedness, flintiness, good faith, heartiness,
   heat, heatedness, homage, impassionedness, imperative,
   indefatigability, industriousness, industry, inflexibility,
   insistence, insistency, intensity, intentness, line of duty,
   mission, must, obedience, obediency, obligation, observance,
   obstinacy, onus, ought, passion, passionateness, patience,
   patience of Job, patriotism, permanence, perseverance, persistence,
   persistency, pertinaciousness, pertinacity, piety, place, plodding,
   plugging, preoccupation, relentlessness, reliability, resolution,
   resolve, respect, rigidity, sedulity, sedulousness,
   self-imposed duty, seriousness, service, servility, servitium,
   settledness, sincerity, single-mindedness, singleness of purpose,
   slogging, spirit, stability, stamina, staunchness, staying power,
   steadfastness, steadiness, steeliness, stick-to-itiveness,
   stubbornness, submission, submissiveness, suit and service,
   suit service, tenaciousness, tenacity, tie, tirelessness, troth,
   true blue, trueness, trustworthiness, truth, unremittingness,
   unswerving attention, unyieldingness, vehemence, warmth,
   willingness, zeal



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

LOYALTY. That which adheres to the law, that which sustains an existing
government. See Penal Laws of China, 3.