1. (adjective) not serious in content or attitude or behavior

• airheaded
• dizzy
• empty-headed
• featherbrained
• giddy
• light-headed
• lightheaded
• silly
• flighty
• flyaway
• head-in-the-clouds
• scatterbrained
• flippant
• light-minded
• idle
• light
• light
• trivial

1. (adjective) not serious in content or attitude or behavior

• superficial

1. (adjective) not serious in content or attitude or behavior

• buffoonery
• clowning
• frivolity
• harlequinade
• japery
• prank
• frivolity
• frivolity
• frivolousness
• frivolousness

1. (adjective) not serious in content or attitude or behavior

• serious