noun

Extraterrestrial Being: A hypothetical or fictional being from another planet or galaxy.
Foreigner: Someone who comes from a different country or culture.

adjective

Foreign or Strange: Something that is not familiar or that comes from a different place or culture.
Unrelated or Unconnected: Not related or relevant to something, like "alien concepts" that don't fit with what is already known or accepted.

Example

noun

1. We saw an alien spacecraft flying in the sky.
2. Scientists believe that aliens exist on other planets.
3. My aunt claims to have been abducted by aliens.

adjective

1. He had an alien idea of how to solve the problem.
2. His speech was filled with alien concepts.
3. She felt an alien sensation as she looked around the room.