the.com/aliens

means Beings originating somewhere other than Earth — hypothetical extraterrestrial life — though the word also covers anyone or anything regarded as foreign or out of place.

from From Latin 'alienus,' meaning 'belonging to another,' built on 'alius' (other) — the same root that gives us 'alias' and 'alibi.' For centuries 'alien' simply meant a foreigner, a stranger, someone not of your land. The sense of 'creature from another world' is a much later stretch of that same idea: the ultimate foreigner, not from another country but another planet. The cosmic meaning bloomed in 20th-century science fiction, but the bones of the word are ancient and earthbound — it always just meant 'the other.'