The Collaborative International Dictionary of English v.0.48:

Eagerness \Ea"ger*ness\, n.
   1. The state or quality of being eager; ardent desire. "The
      eagerness of love." --Addison.
      [1913 Webster]

   2. Tartness; sourness. [Obs.]

   Syn: Ardor; vehemence; earnestness; impetuosity; heartiness;
        fervor; fervency; avidity; zeal; craving; heat; passion;
        greediness.
        [1913 Webster]

WordNet (r) 3.0 (2006):

eagerness
    n 1: a positive feeling of wanting to push ahead with something
         [syn: eagerness, avidity, avidness, keenness]
    2: prompt willingness; "readiness to continue discussions";
       "they showed no eagerness to spread the gospel"; "they
       disliked his zeal in demonstrating his superiority"; "he
       tried to explain his forwardness in battle" [syn:
       readiness, eagerness, zeal, forwardness]

Moby Thesaurus II by Grady Ward, 1.0:

165 Moby Thesaurus words for "eagerness":
   OK, a thing for, acceptance, accord, acquiescence, affinity,
   affirmation, affirmative, affirmative voice, agreeability,
   agreeableness, agreement, alacrity, ambition, amenability,
   animation, anxiety, appetite, approbation, approval, aptitude,
   aptness, ardor, assent, avidity, aye, bent, bias, blessing,
   breathless impatience, cast, chafing, cheerful consent, compliance,
   conatus, concupiscence, conduciveness, connivance, consent,
   cooperativeness, curiosity, dash, delight, desideration, desire,
   diathesis, disposition, disquietude, docility, drive, earnestness,
   elan, endorsement, energy, enthusiasm, excitement, fancy, fantasy,
   favorable disposition, favorableness, feeling for, fervor,
   forwardness, fretfulness, fretting, gameness, get-up-and-go, go,
   goodwill, gusto, haste, hope, horme, hunger, impatience,
   impatientness, impetuousness, inclination, intellectual curiosity,
   keenness, lather, leaning, liability, libido, liking, longing,
   lust for learning, mind, mustard, need, okay, passion, penchant,
   permission, pleasure, pleasure principle, pliability, pliancy,
   predilection, predisposition, prejudice, probability, proclivity,
   promptitude, promptness, proneness, propensity, quickness,
   ratification, readiness, receptive mood, receptiveness,
   receptivity, relish, responsiveness, restiveness, restlessness,
   right mood, sanction, sensitivity to, sexual desire, soft spot,
   spirit, spiritedness, stew, submission, susceptibility, sweat,
   tendency, tense readiness, thirst for knowledge, tractability,
   tropism, turn, twist, uneasiness, ungrudgingness, unloathness,
   unpatientness, unquietness, unreluctance, urge, vehemence, verve,
   vigor, vim, vitality, want, wanting, warp, weakness, will,
   will and pleasure, willing ear, willing heart, willingness, wish,
   wish fulfillment, wishing, yearning, zeal, zealousness, zest, zing,
   zip