Based on Legal Status:
* Non-citizen: This is the most direct opposite, referring to someone who is not a citizen of a particular country.
* Alien: This term can be considered outdated and may carry negative connotations. It refers to someone who is not a citizen of the country they are residing in.
* Resident alien: This term describes someone who is legally residing in a country but is not a citizen.
* Stateless: This refers to someone who does not have citizenship in any country.
Based on Political Participation:
* Subject: This term suggests someone who is under the rule of a government but does not have the same rights and freedoms as a citizen.
* Subordinate: This implies someone who is under the authority of another, lacking autonomy and political power.
* Non-voter: This refers to someone who is eligible to vote but chooses not to participate in the political process.
* Apolitical: This describes someone who is not interested in or involved in politics.
Based on Social Engagement:
* Outsider: This refers to someone who is not considered part of a particular community or society.
* Stranger: This suggests someone who is unfamiliar or unknown within a specific group.
* Alienated: This describes someone who feels isolated, disconnected, or excluded from a community.
Ultimately, the best opposite of "citizen" depends on the specific context and meaning you want to convey.