What is a synonym the word intentional?

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

Formal:

* Deliberate

* Premeditated

* Designed

* Purposeful

* Calculated

* Conceived

* Planned

Informal:

* On purpose

* Meant to

* Deliberately

* Knowingly

Other options:

* Willful

* Conscious

* Voluntary

* Motivated

The best synonym for "intentional" will depend on the specific situation and the desired level of formality.