What is a antonym of the word intentional?

Here are some antonyms for "intentional", depending on the specific context:

General Antonyms:

* Accidental

* Unintentional

* Unwitting

* Involuntary

* Unplanned

* Fortuitous

* Chance

* Coincidental

More Specific Antonyms:

* Careless (if referring to a lack of attention to detail)

* Negligent (if referring to a lack of responsibility)

* Random (if referring to something without a specific goal)

* Unconscious (if referring to something done without awareness)

The best antonym will depend on the specific meaning you're trying to convey.