1. a person who speaks in a low, unclear way that is difficult to understand

Examples

• The teacher asked the mumbler to speak more clearly.
• He’s such a mumbler that I can never understand what he’s saying.
• The mumbler at the back of the room needs to project his voice.
• She was known as a mumbler who always spoke under her breath.
• The mumbler’s presentation was hard to follow because of his unclear speech.
• Don’t be a mumbler during your job interview.