Vindictive describes a person who wants to hurt someone back, and wants it too much. Someone hurt them, and instead of letting it go, they carry the anger for a long time and look for ways to make that person suffer — often in ways far bigger than the original harm. A vindictive ex-partner tells lies to your friends for years. A vindictive boss gives you the worst jobs because you once disagreed in a meeting. This is always a criticism. There is no kind version of this word. That is what separates it from simply wanting fairness: if a thief is sent to prison, that is justice, and nobody calls it vindictive; but if the person they stole from also gets them fired, spreads their name around town, and follows them to their new job, that is vindictive. The line is proportion — and coldness. A vindictive person is not exploding in the moment; they are patient, which is what makes it frightening. It can also describe actions and things, not only people: a vindictive email, a vindictive punishment, a vindictive streak. And notice it is stronger and colder than angry, and narrower than cruel — cruelty can be aimed at anyone, but vindictiveness is always payback aimed at someone who wronged you first.