Related Clues:

• 'Silence!'
• Request for quiet
• Quietude
• "Quiet now"
• Teacher's admonition
• Reaction to a library volume?
• Library admonishment
• "Zip it!"
• __ money
• 'Stifle!'
• 'Shut yo' mouth!'
• It may precede 'Don't let anyone hear!'
• "No whispering!"
• Library reminder
• You can break it merely by mentioning it