This is the 10170th most frequent French word.
illicites
Illegal.
The word 'illicites' here is used as an adjective describing 'activités'. It indicates that the activities mentioned are illegal or forbidden by law.
Les activités illicites peuvent entraîner de graves conséquences.
Illicit activities can lead to severe consequences.
In this sentence, 'illicites' is again used as an adjective modifying 'substances', referring to substances that are prohibited or illegal.
Ils ont été arrêtés pour possession de substances illicites.
They were arrested for possession of illicit substances.
Here, the adjective 'illicites' is used to describe 'produits', indicating that the products being discussed are not permitted under the law.