vi·vac·i·ty /-ˈvæsəti/
  快活,活潑,精神充沛
  Vi·vac·i·ty n.  The quality or state of being vivacious.  Specifically: --
  (a) Tenacity of life; vital force; natural vigor.  [Obs.]
     The vivacity of some of these pensioners is little less than a miracle, they lived so long.   --Fuller.
  (b) Life; animation; spiritedness; liveliness; sprightliness; as, the vivacity of a discourse; a lady of great vivacity; vivacity of countenance.
  Syn: -- Liveliness; gayety.  See Liveliness.
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  vivacity
       n : characterized by high spirits and animation