Done deliberately; intended.
An intentional slight.
Having to do with intention or purpose.
Having to do with intention.
Done purposely; intended.
The definition of intentional is something done on purpose.
If you specifically make a plan to be nice to someone you don't like very much and you are extremely careful to be nice, this is an example of when your nice behavior would be described as intentional.
Origin of intentional
intention + -al