Source : Webster's Revised Unabridged Dictionary (1913)

Vivacious \Vi*va"cious\ (?; 277), a. [L. v['i]vax, -acis, fr.
   vivere to live. See {Vivid}.]
   1. Having vigorous powers of life; tenacious of life;
      long-lived. [Obs.]

            Hitherto the English bishops have been vivacious
            almost to wonder. . . . But five died for the first
            twenty years of her [Queen Elizabeth's] reign.
                                                  --Fuller.

            The faith of Christianity is far more vivacious than
            any mere ravishment of the imagination can ever be.
                                                  --I. Taylor.

   2. Sprightly in temper or conduct; lively; merry; as, a
      vivacious poet. ``Vivacious nonsense.'' --V. Knox.

   3. (Bot.) Living through the winter, or from year to year;
      perennial. [R.]

   Syn: Sprightly; active; animated; sportive; gay; merry;
        jocund; light-hearted. -- {Vi*va"cious*ly}, adv. --
        {Vi*va"cious*ness}, n.

Source : WordNet®

vivacious
     adj : vigorous and active; "a vibrant group that challenged the
           system"; "a charming and vivacious hostess"; "a
           vivacious folk dance" [syn: {vibrant}]