Xenophobia denotes a phobic attitude toward strangers or of the unknown. It comes from the Greek word xenos, meaning "foreigner," "stranger," and phobos, meaning "fear." The term is typically used to describe fear or dislike of foreigners or in general of people different from one's self. For example, racism is sometimes described as a form of xenophobia. In science fiction, it has come to mean "fear of extraterrestrial things." Xenophobia implies a belief, accurate or not, that the target is in some way foreign. Prejudice against women cannot be considered xenophobic in this sense, except in the limited case of all-male clubs or institutions. The term xenophilia is used for the opposite behavior, attraction to or love for foreign persons.
The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, 4th edition ("DSM-IV") includes in its description of a phobia an "intense anxiety" which follows exposure to the "object of the phobia, either in real life or via imagination or video..." For xenophobia there are two main objects of the phobia. The first is a population group present within a society, which is not considered part of that society. Often they are recent immigrants, but xenophobia may be directed against a group which has been present for centuries. This form of xenophobia can elicit or facilitate hostile and violent reactions, such as mass expulsion of immigrants, or in the worst case, genocide.
The second form of xenophobia is primarily cultural, and the object of the phobia is cultural elements which are considered alien. All cultures are subject to external influences, but cultural xenophobia is often narrowly directed, for instance at foreign loan words in a national language. It rarely leads to aggression against persons, but can result in political campaigns for cultural or linguistic purification. Isolationism, a general aversion of foreign affairs, is not accurately described as xenophobia.