illegal
He wants to find out if the companies acted illegally.
Internet users who illegally download movies and music can have their web access blocked.
They illegally obtained information from her personnel file.

SMART Vocabulary: related words and phrases

Legal & illegal
bang to rightsidiom
bookable
bootleg
chargeable
concealed carryidiom
controverted election
criminally
illegality
improper
legitimate
licensed
licit
licitly
non-criminal
non-legal
shady
treasonable
unlawful
validity
validly