The Collaborative International Dictionary of English v.0.48:

Liveliness \Live"li*ness\, n. [From Lively.]
   1. The quality or state of being lively or animated;
      sprightliness; vivacity; animation; spirit; as, the
      liveliness of youth, contrasted with the gravity of age.
      --B. Jonson.
      [1913 Webster]

   2. An appearance of life, animation, or spirit; as, the
      liveliness of the eye or the countenance in a portrait.
      [1913 Webster]

   3. Briskness; activity; effervescence, as of liquors.
      [1913 Webster]

   Syn: Sprightliness; gayety; animation; vivacity; smartness;
        briskness; activity. -- Liveliness, Gayety,
        Animation, Vivacity. Liveliness is an habitual
        feeling of life and interest; gayety refers more to a
        temporary excitement of the animal spirits; animation
        implies a warmth of emotion and a corresponding
        vividness of expressing it, awakened by the presence of
        something which strongly affects the mind; vivacity is a
        feeling between liveliness and animation, having the
        permanency of the one, and, to some extent, the warmth
        of the other. Liveliness of imagination; gayety of
        heart; animation of countenance; vivacity of gesture or
        conversation.
        [1913 Webster]

WordNet (r) 3.0 (2006):

liveliness
    n 1: general activity and motion [syn: liveliness,
         animation]
    2: animation and energy in action or expression; "it was a heavy
       play and the actors tried in vain to give life to it" [syn:
       liveliness, life, spirit, sprightliness]