Related Clues:

• Nonchalant
• Like an atrium
• Having no perceptible weight
• Open to breezes
• Poorly sealed, maybe
• Vacuous
• Having open windows, maybe
• Open-roofed
• Bright and breezy
• Hardly airtight
• Immaterial
• Light and breezy
• Vivacious
• Exceptionally light
• Not well insulated