illegally
adv.in a way that breaks the law. You use this when someone does something that is not allowed by the government or official rules.
adv.in a manner that contravenes established law or official regulations.
“He was fined for parking his car illegally.”
“The company was caught dumping waste illegally into the river and faced a massive fine.”
“While the protesters claimed their actions were morally justified, the court ruled that they had entered the private facility illegally and were liable for damages.”
Typically placed after the verb or at the end of the clause; can also precede the past participle in passive constructions.
When following a preposition like 'for', the action must be a gerund (-ing form), not the base verb.
From illegal + -ly or il- + legally.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.