What might be an appropriate synonym for 'boring' as expressed by the man?

The word 'boring' conveys a lack of interest or excitement, and a synonym for that would need to embody a similar meaning. 'Uninteresting' fits perfectly in this context because it directly reflects the idea of something that fails to capture attention or curiosity. When something is described as uninteresting, it implies that it does not engage or stimulate the audience, which aligns with the feeling of boredom.

In contrast, the other words like 'fascinating,' 'engaging,' and 'captivating' all suggest a sense of interest and excitement, which is the opposite of what 'boring' means. These options would not be appropriate synonyms since they imply the presence of intrigue and stimulation rather than a lack of it. Thus, 'uninteresting' is the most fitting choice as a synonym for 'boring.'