Illegal – English Flashcard for Illegal for IELTS Updated: February 25, 2021 by Dr. Mohammad Hossein Hariri AslIllegal Illegal (adj) /ɪˈliː.gəl/against the law, unlawful, not supported by law, illegitimate, prohibited, forbidden, bannedIllegal immigration is a serious social issue these days.Antonym: legalAdverb: illegally