This is the 4432nd most frequent French word.
illégal
Not lawful or permitted by law; illegal.
Here, 'illégal' is used to describe an action, parking in this place, that is against the law.
C'est illégal de stationner ici.
It's illegal to park here.
In this sentence, 'illégal' qualifies the noun 'accord,' illustrating a prohibited or unauthorized state of the agreement.
Cet accord est illégal selon les lois locales.
This agreement is illegal according to local laws.
The adjective 'illégal' is used to emphasize the legal restriction against disseminating false information.