What is the antonym of amusment?

There isn't a single perfect antonym for "amusement" as it depends on the context. Here are some possibilities:

If you're thinking of amusement as a feeling of enjoyment:

* Boredom

* Displeasure

* Disinterest

* Tedium

* Dullness

If you're thinking of amusement as an activity or entertainment:

* Work

* Duty

* Seriousness

* Responsibility

If you're thinking of amusement as a way to laugh or find something funny:

* Seriousness

* Solemnity

* Gravity

The best antonym will depend on the specific situation and what you're trying to convey.