Illicit Trade

noun a system in which goods or services are bought and sold illegally, usually to avoid government regulations or taxes

• The government is cracking down on the black market for counterfeit goods.
• I heard you can get cheap electronics on the black market.
• Don't mess with the black market, it's too risky.
• His reputation on the black market of gossip was unmatched.

noun a person, place, thing, or idea

adjective a word that describes or modifies a noun or pronoun

• The authorities are cracking down on illicit business activities in the city.
• I heard that some of the guys are involved in some shady business deals.
• They're running an underground operation, doing some sketchy business on the side.
• The illicit business of spreading rumors can be just as damaging as any other illegal activity.