Black market

system for selling goods illegally

The underground economy, shadow economy, black economy, or black market consists of all commerce on which applicable taxes are being evaded. The market includes not only legally-prohibited commerce (for example, drugs, prostitution, and gambling activities that are illegal in some locales), but also trade in legal goods and services because some income is not reported and consequently taxation is evaded, e.g., through money laundering, payment in caeconomy, or black market consists of all commerce on which applicable taxes are being evaded.
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Noun
1. people who engage in illicit trade
(hypernym) market
(member-meronym) black marketeer
(derivation) run
2. an illegal market in which goods or currencies are bought and sold in violation of rationing or controls
(hypernym) market, marketplace
(derivation) run
Verb
1. deal in illegally, such as arms or liquor
(synonym) run
(hypernym) trade, merchandise
(verb-group) ply, run
(classification) crime, law-breaking

Adjective
1. distributed or sold illicitly; "the black economy pays no taxes"
(synonym) bootleg, black, contraband, smuggled
(similar) illegal

An illegal market.