What is an antonym for astonishing?

Here are some antonyms for astonishing, depending on the context:

General antonyms:

* Ordinary

* Commonplace

* Unremarkable

* Unimpressive

* Boring

* Expected

* Predictable

Antonyms related to surprise:

* Expected

* Predictable

* Dull

* Uninteresting

* Unremarkable

Antonyms related to awe:

* Disappointing

* Mediocre

* Trivial

* Uninspiring

The best antonym for "astonishing" will depend on the specific situation and the intended meaning.