Related Clues:

• Lacking energy
• Well fixed
• Like noble gases
• Listless
• Lethargic, perhaps
• Like radon
• Like krypton and xenon
• Languid
• Inanimate
• Lacking liveliness
• Like neon and xenon
• Like neon and argon
• Opposite of active
• Like xenon and helium
• Perfectly still