adjective
Definition: Describing something that is spoken or presented in a flat, unchanging tone, or something that has only one color or shade.
Example: The teacher's monotone voice made it hard for the students to stay awake during the lecture.
noun
Definition: A sound or voice that stays at the same pitch without changing, often making it sound dull or boring.
Example: The teacher spoke in a monotone, making it hard for the students to stay awake.