non-member state; non-member nation
Refers to a country that is not a member of a particular international organization or treaty.
That country is a non-member state of the United Nations.
Non-member nations can also participate in the conference as observers.
加盟国 means 'member state', the opposite of 非加盟国.
Compound of 非 (hi, 'non-') + 加盟 (kamei, 'affiliation') + 国 (koku, 'country').