If you pervert something such as a process or society, you interfere with it so that it is not as good as it used to be or as it should be.

If someone perverts the course of justice, they deliberately do something that will make it difficult to discover who really committed a particular crime, for example, destroying evidence or lying to the police.

If you say that someone is a pervert, you mean that you consider their behaviour, especially their sexual behaviour, to be immoral or unacceptable.