1. An unlawful or unofficial route, method, or channel used to accomplish something outside of proper legal or administrative procedures
The documents were obtained via irregular means.
Os documentos foram obtidos por via irregular.
2. In legal and administrative contexts, a method that does not follow standard protocols or regulations
The approval came via irregular procedures.
A aprovação veio por via irregular.
3. An informal or clandestine pathway for conducting business or transactions
He conducted his affairs via irregular channels.
Ele conduzia seus negócios por vias irregulares.