The Collaborative International Dictionary of English v.0.48:

Ebullient \E*bul"lient\, a. [L. ebulliens, -entis, p. pr. of
   ebullire to boil up, bubble up; e out, from + bullire to
   boil. See 1st Boil.]
   Boiling up or over; hence, manifesting exhilaration or
   excitement, as of feeling; effervescing. "Ebullient with
   subtlety." --De Quincey.
   [1913 Webster]

         The ebullient enthusiasm of the French.  --Carlyle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ebullient
    adj 1: joyously unrestrained [syn: ebullient, exuberant,
           high-spirited]