In law, an alien is any person (including an organization) who is not a citizen or a national of a specific country, although definitions and terminology differ to some degree depending upon the continent or region. More generally, however, the term "alien" is perceived as synonymous with foreign national. Lexicology The term "alien" is derived from the Latin alienus, which in turn is derived from the Oscan mancupatis, (a proto-Etruscan tribe), meaning a slave. The Latin later came to mean a stranger, a foreigner, or someone not related by blood. Similar terms to "alien" in this context include foreigner and lander. Categories Different countries around the world use varying terms for aliens. The following are several types of aliens: legal alien any foreign national who is permitted under the law to be in the host country. This is a very broad category which includes travel visa holders or foreign tourists, registered refugees, temporary residents, permanent residents, and those who have relinquished their citizenship and/or nationality. Categories of legal alien include temporary resident alien any foreign national who has been lawfully granted permission by the government to drive, fly, travel, lodge, reside, study or work for a specific number of years and then apply for an extension or leave the country before such permission expires. permanent resident alien any immigrant who has been lawfully admitted into a nation and granted the legal right to remain therein as a permanent resident in accord with the nation's immigration laws. nonresident alien any foreign national who is lawfully within a nation but whose legal domicile is in another nation. alien enemy (or enemy alien) any foreign national of any country that is at war with the host country. undocumented alien (or illegal alien) any person who is liable to deportation because their presence in a nation is in violation of that nation's immigration laws. Common law jurisdictions An "alien" in English law denoted any person born outside of the monarch's dominions and who did not owe allegiance to the monarch. Aliens were not allowed to own land and were subject to different taxes to subjects. This idea was passed on in the Commonwealth to other common law jurisdictions. Australia In Australia, citizenship is defined in the Australian nationality law. Non-citizens in Australia are permanent residents, temporary residents, or illegal residents (technically called "unlawful non-citizens"). Most non-citizens (including those who lack citizenship documents) traveling to