Related Clues:

• Dull fellow
• Real bore
• Barrel's inside diameter
• Display of disinterest
• Gun barrel diameter
• Show boredom
• Exhibit ennui
• Sign of fatigue
• 'When is this thing over?'
• Unwanted guest, maybe
• Open wide?
• Tidal wave
• Impatient gesture
• Sleepiness sign
• Put to sleep, so to speak