Monotone is a term that describes a flat, unvarying tone or voice. The term "more monotone" might be used to describe a voice or a piece of music that lacks variation, emphasizing a lack of emotion or inflection. Antonyms, on the other hand, are words that have opposite or contrasting meanings. In this case, antonyms for "more monotone" might include words like expressive, dynamic, lively, animated, or passionate. Using these words to describe speech or music suggests a greater range of inflection, tone, and emotional emphasis, indicating a speaker or performer who engages and captivates the listener.