Illicit business can refer to any activity that is illegal or unethical, such as the sale of drugs, weapons, or stolen goods. However, the term is quite broad and can encompass a wide range of illegal practices. As such, there are many synonyms that can be used to describe different types of illicit business. These include terms like black market, underground economy, shadow economy, gray market, and informal economy. While these terms may have slightly different connotations and imply different types of illegal activities, they all refer to businesses that operate outside of the law and typically involve the exchange of goods or services that are considered illegal or harmful to society.