Monotone/ˈmɑːnətəʊn/ Definition 1 of 4Pro Tip 1/3Lack of Emotion Monotone voices are often perceived as lacking emotion or enthusiasm. He answered the phone with a monotone 'hello', sounding disinterested. Pro Tip 2/3Boredom Effect Using a monotone voice might unintentionally cause listeners to feel bored. The lecturer's monotone speech made the students yawn. Pro Tip 3/3Robotic Tone A monotone voice can sound robotic, lacking the usual ups and downs of speech. Her monotone recital made her sound like a robot.