What is he antonym of delightful?

The antonym of delightful depends on the specific context. Here are some possibilities:

General Antonyms:

* Unpleasant

* Disagreeable

* Unenjoyable

* Awful

* Horrible

* Dreadful

* Repulsive

* Offensive

More Specific Antonyms:

* Disappointing (if referring to an experience)

* Depressing (if referring to a mood or atmosphere)

* Distressing (if referring to something causing emotional pain)

* Painful (if referring to a physical sensation)

* Boring (if referring to something lacking interest)

* Tedious (if referring to something tiresome)

* Monotonous (if referring to something lacking variety)

To determine the best antonym, consider the specific situation in which you're using the word "delightful."