illegal

(noun): An illegal act or technique.
(noun): (plural, as illegals) Contraband, esp. illegal substances such as drugs.
(noun): An illegal immigrant.
(noun): A spy working abroad illegally and undercover, without visible ties to his or her country’s authorities.
(adjective): Contrary to or forbidden by law, especially criminal law.
(adjective): Forbidden by established rules.
(adjective): (of an issue printed for collectors) Totally fictitious, and often issued on behalf of a non-existent territory or country.
(adjective): (of a person, sometimes offensive) Being or doing something illegally.
(adjective): (sometimes offensive) Being an illegal immigrant; residing in a country illegally.