The Collaborative International Dictionary of English v.0.48:

Vivacity \Vi*vac"i*ty\, n. [L. vivicitas: cf. F. vivacit['e].]
   The quality or state of being vivacious. Specifically:
   [1913 Webster]
   (a) Tenacity of life; vital force; natural vigor. [Obs.]
       [1913 Webster]

             The vivacity of some of these pensioners is little
             less than a miracle, they lived so long. --Fuller.
       [1913 Webster]
   (b) Life; animation; spiritedness; liveliness; sprightliness;
       as, the vivacity of a discourse; a lady of great
       vivacity; vivacity of countenance.
       [1913 Webster]

   Syn: Liveliness; gayety. See Liveliness.
        [1913 Webster]

WordNet (r) 3.0 (2006):

vivacity
    n 1: characterized by high spirits and animation

Moby Thesaurus II by Grady Ward, 1.0:

94 Moby Thesaurus words for "vivacity":
   activity, alacrity, animal spirits, animate existence, animation,
   anxiety, anxiousness, appetite, ardor, avidity, avidness,
   being alive, birth, breathless impatience, breeziness, brio,
   briskness, bubbliness, capersomeness, cheerful readiness,
   coltishness, dash, eagerness, ebullience, effervescence, elan,
   energy, enthusiasm, esprit, existence, exuberance, forwardness,
   friskiness, frolicsomeness, gaiety, gamesomeness, gayness, glow,
   gust, gusto, having life, heartiness, immortality, impatience,
   impetuosity, impetus, joie de vivre, keen desire, keenness, life,
   lifetime, liveliness, living, long life, longevity, lustiness,
   mettle, moxie, pep, peppiness, perkiness, pertness, piquancy,
   piss and vinegar, pizzazz, playfulness, poignancy, promptness,
   pungency, quickness, raciness, readiness, robustness,
   rollicksomeness, rompishness, skittishness, sparkle, spirit,
   spiritedness, spirits, sportiveness, sprightliness, spriteliness,
   verve, viability, vigor, vim, vitality, vivaciousness, vividness,
   warmth, zest, zestfulness, zip