adj. & n.
adj. 1 a (often foll. by to) unfamiliar; not in accordance or harmony; unfriendly, hostile; unacceptable or repugnant (army discipline was alien to him; struck an alien note). b (often foll. by from) different or separated. 2 foreign; from a foreign country (help from alien powers). 3 of or relating to beings supposedly from other worlds. 4 Bot. (of a plant) introduced from elsewhere and naturalized in its new home.
n. 1 a foreigner, esp. one who is not a naturalized citizen of the country where he or she is living. 2 a being from another world. 3 Bot. an alien plant. alienness n.
[ ME f. OF f. L alienus belonging to another (alius) ]