This is the 8474th most frequent Russian word.
незаконный
Illegal.
The word 'незаконную' is used as an adjective describing 'деятельность', denoting activities that are against the law.
Он был арестован за незаконную деятельность.
He was arrested for illegal activities.
Here, 'незаконным' serves as an adverbial addition to 'образом', implying actions carried out contrary to the law in terms of construction.
Этот дом был построен незаконным образом.
This house was built in an illegal manner.
The term 'незаконные' describes 'действия', indicating behaviors that violate legal standards and have consequences.