1ADJ [usually ADJ n]外国的;异族的Alien means belonging to a different country, race, or group, usually one you do not like or are frightened of. 外国的;异族的 [formal, disapproval]
He said they were opposed to the presence of alien forces in the region.
2ADJ-GRADED [usually ADJ n]怪异的;可怕的;异己的 You use alien to describe something that seems strange and perhaps frightening, because it is not part of your normal experience. 怪异的;可怕的;异己的
3ADJ-GRADED 陌生的;格格不入的;不相容的 If something is alien to you or to your normal feelings or behaviour, it is not the way you would normally feel or behave. 陌生的;格格不入的;不相容的 [formal]
Such an attitude is alien to most businessmen. [+ to]
大多数商界人士都会对这样的态度感到陌生。
4N-COUNT 外国人 An alien is someone who is not a legal citizen of the country in which they live. 外国人 [formal, law]
Both women had hired illegal aliens for child care.
两个女人都曾雇过非法入境者照看孩子。
When war broke out, he was interned as an enemy alien.