Related Clues:

• "Zip it!"
• "Stifle yourself!"
• 'Hush up!'
• Ironic thing to shout
• Noiseless
• Calm, hushed
• Tranquil, calm
• "Be quiet!"
• ''Shut your mouth!''
• 'Zip your lips!'
• "Put a lid on it!"
• "Zip your lip!"
• Leave note in it for mum
• Keep quiet aboard ship
• Not stormy, but quite changeable