Frivolity is lighthearted silliness or playfulness that doesn't take things seriously. When your class erupts in frivolity during a lesson, everyone's giggling and making jokes instead of focusing on the work. A birthday party full of frivolity might include silly games, goofy hats, and lots of laughter.

The word often suggests that serious things are being treated too lightly. If a student council meeting dissolves into frivolity, members are joking around when they should be making important decisions. During a solemn ceremony, frivolity would feel inappropriate and disrespectful.

There's a time and place for frivolity. Recess and lunch are perfect for it. A serious discussion about someone's hurt feelings is not. The related adjective is frivolous, which describes something silly or not important: a frivolous purchase might be a toy you don't need and will barely use, while a frivolous excuse is one that doesn't hold up to scrutiny.