What is an antonym for the word interesting?

There isn't one perfect antonym for "interesting" as it depends on the context. Here are some options depending on what you mean:

If you mean "lacking in excitement or novelty":

* Boring

* Dull

* Tedious

* Monotonous

* Uninspiring

* Unremarkable

If you mean "not worthy of attention":

* Uninteresting

* Irrelevant

* Trivial

* Insignificant

* Meaningless

If you mean "unappealing":

* Repulsive

* Offensive

* Disgusting

* Unpleasant

If you mean "not thought-provoking":

* Superficial

* Shallow

* Simple

* Uninformative

Ultimately, the best antonym will depend on the specific context in which you are using the word "interesting."