noun

the state or quality of being light-hearted or cheerful.

the sudden gaiety of children’s laughter

cheerfulness,cheer,light-heartedness,merriment,glee,gladness,happiness,joy,joyfulness,joyousness,delight,pleasure,high spirits,good spirits,good humour,jollity,jolliness,hilarity,mirth,joviality,exuberance,elation,exultation,euphoria,jubilation,liveliness,vivacity,animation,effervescence,levity,buoyancy,sprightliness,zest,zestfulness,joie de vivre,chirpiness,bounce,pep,zing,gladsomeness,blitheness,blithesomeness,gayness