Related Clues:

• "Shush!"
• 'Shhh!,' not so politely
• Request for quiet
• Teacher's admonition
• Reaction to a library volume?
• Library admonishment
• "Zip it!"
• 'Stifle!'
• It may precede 'Don't let anyone hear!'
• "No whispering!"
• Library reminder
• Silencing sound
• "Stifle yourself!"
• "Quiet, please!"
• 'Zip it up!'