Related Clues:

• Tedious talker
• Droner, often
• Uninteresting storyteller
• Dull fellow
• Barrel's inside diameter
• Gun barrel diameter
• Motormouth
• Unwanted guest, maybe
• Tidal wave
• Put to sleep, so to speak
• Tedious fellow
• One causing ennui
• Drill holes
• Incessant talker
• Make weary by being dull