- forbidden by law or statute.
- contrary to or forbidden by official rules, regulations, etc.: The referee ruled that it was an illegal forward pass.
- Informal: Disparaging and Offensive. illegal alien.
- forbidden by law; unlawful; illicit
- unauthorized or prohibited by a code of official or accepted rules
- a person who has entered or attempted to enter a country illegally
1620s, from French illégal or directly from Medieval Latin illegalis, from assimilated form of in- “not, opposite of” (see in- (1)) + Latin legalis (see legal). Term illegal immigrant first recorded 1892 in American English (illegal immigration is from 1887).