In social studies, an alien is not a person from another planet. Instead, the word is typically used to mean someone who comes to a country from another country. That person is said to be an "alien" in the country to which he or she has migrated. You can easily imagine a number of sentences that would use alien in this way. For example:
- People in the country became frustrated with the large numbers of aliens who entered their country illegally.
- In that country, aliens do not enjoy all of the same rights and privileges that citizens of the country do.