Vendicare vs. vendicarsi
The Italian words 'vendicare' and 'vendicarsi' both relate to the concept of revenge, but they differ in their usage and grammatical structure.
Vendicare
'Vendicare' is a transitive verb meaning to avenge or take revenge on someone or something.
Lui vuole vendicare la morte di suo padre.
(He wants to avenge his father's death.)
La polizia cerca di vendicare le vittime del crimine.
(The police try to avenge the victims of the crime.)
Vendicarsi
'Vendicarsi' is a reflexive verb meaning to take revenge for oneself or to get even.
Maria si è vendicata del suo ex-ragazzo.
(Maria got revenge on her ex-boyfriend.)
Non vale la pena vendicarsi per cose così piccole.
(It's not worth taking revenge for such small things.)
Summary
While 'vendicare' is used when someone takes revenge on behalf of another person or for a cause, 'vendicarsi' is used when someone takes revenge for themselves. 'Vendicare' requires a direct object, whereas 'vendicarsi' is followed by 'di' or 'su' to indicate the target of revenge.