Which term is synonymous with "boring; unvarying in tone or content"?

The term "monotonous" precisely captures the essence of being "boring; unvarying in tone or content." It describes a situation or material that lacks variety and interest, often characterized by an unchanging tone that can dull the senses or evoke a sense of tedium. In this context, the word suggests a repetitive quality that fails to engage or stimulate, making it synonymous with the given phrase.

The term encapsulates a sense of uniformity that can lead to disinterest or fatigue, aligning perfectly with the notion of being unexciting or lacking in variation. This quality makes "monotonous" the most fitting choice for conveying the idea of something that is both boring and consistent in its presentation.