Related Clues:

• Tedious sort
• Drip
• Yawn-inducing speaker, say
• What unexciting drillers do?
• Tedious talker
• Droner, often
• Uninteresting storyteller
• Dull fellow
• Barrel's inside diameter
• Gun barrel diameter
• Motormouth
• Magpie, e.g.
• Unwanted guest, maybe
• Tidal wave
• Put to sleep, so to speak