noun

lack of seriousness; light-heartedness.

a night of fun and frivolity

light-heartedness,levity,joking,jocularity,gaiety,fun,frivolousness,silliness,foolishness,zaniness,giddiness,flightiness,skittishness,flippancy,facetiousness,inanity,superficiality,shallowness,vacuity,empty-headedness,dizziness,dippiness,daftness,ditziness