1. not serious; lacking gravity, importance, or earnestness

Examples

• His unserious attitude toward the project concerned his teammates.
• The comedian’s unserious approach to politics entertained the audience.
• She dismissed the criticism as unserious and poorly researched.
• The meeting took an unserious turn when jokes started flying.
• Critics called the proposal unserious and lacking in detail.
• His unserious demeanor masked his deep knowledge of the subject.