noun

the quality of being cheerful and full of energy; exuberance.

the ebullience of happy children

exuberance,buoyancy,cheerfulness,joy,joyfulness,gladness,cheeriness,merriment,jollity,sunniness,breeziness,jauntiness,light-heartedness,high spirits,high-spiritedness,exhilaration,elation,euphoria,jubilation,animation,sparkle,effervescence,vivacity,enthusiasm,zest,irrepressibility,perkiness,bubbliness,chirpiness,bounciness,pep,zing,zip,fizz,good cheer