The American Psychological Association defines “anger” as “an emotion characterized by antagonism toward someone or something you feel has deliberately done you wrong.”
The Catechism of the Catholic Church, however, defines “anger” as “a desire for revenge.” (§2302).
A desire for revenge seems more intentional to me than an emotion, which seems more like a reaction – an involuntary one, at that – to someone’s wronging you. I feel I could react with the APA’s kind of anger without being guilty of the Church’s kind. Although maybe if I examined my own motives with sufficient care, I would find that desire for revenge lurking in my emotionally reactive antagonism. But then again, maybe not.