n. a person whose occupation revolves around breaking the law, usually as an extortionist, or as a muscleman supporting persons engaged in some illegal activity.

Plural: _rowdies_ 

A rowdy with a long criminal record is known as rowdy-sheeter

(history-sheeter). Rowdies are also employed by political parties to create trouble, such as riots, vandalism, and other forms of violence. Police stations all over India have to keep track of rowdies in their jurisdictions.

Quite a few rowdies have entered politics and have been elected to

office. The police that used to chase them around neighbourhoods have to suffer the ignominy of having to provide them with official security cover.

This process of criminals and members of organised crime entering

politics is known as the criminalisation of politics.