The antonym of boring is interesting. When something is described as interesting, it means it captures your attention and keeps you engaged. Unlike boring, which implies a lack of excitement or interest, interesting suggests that the subject or activity is enjoyable and worth your time.
For example, a book that is interesting will keep you turning the pages, while a boring book might make you want to put it down. Similarly, a conversation that is interesting will hold your attention, whereas a boring conversation might make you want to change the subject or leave.
In summary, if you find something boring, you can say it is not interesting. Conversely, if something is interesting, it is definitely not boring.