When a person makes a statement which defames another person publicly what is the offense called?

To defame someone, that is, to impair their reputation by making false statements about them, is not usually a criminal offence but rather a civil wrong or tort which forms the basis of a lawsuit. In some jurisdictions this is simply called defamation but in others there are differences in law and procedure depending on whether the defamatory statement was published as an oral statement or as a written one. Oral defamation is called slander whereas written defamation is called libel.