Levity (noun)

The quality of being light in a way that is not serious or appropriate for a particular situation; lack of gravity, seriousness, or earnestness.

Origin:

From the latin levitas, from levis "light".

Examples:

1. His levity during the meeting was not well received.
2. His levity was inappropriate given the serious nature of the discussion.
3. The levity of the situation made it difficult for anyone to take it seriously.
4. His levity was seen as a lack of respect for the gravity of the situation.
5. The levity of his tone belied the importance of the topic at hand.