citizen : 指拥有某国国籍或有某地区合法身份的人，即公民。
- The interests of British citizens living abroad are protected by the British Embassy.
- He applied to become an American citizen.
- The citizens of Moscow woke up this morning to find they had a new government.
- Old people are just treated like second-class citizens (= unimportant people).
- He reassured people that law-abiding citizens (= people who do not break the law) would have nothing to fear from the enquiries.
civilian : 指相对于军人或官员的平民百姓。
- The bomb killed four soldiers and three civilians.
- He left the army and returned to civilian life.
inhabitant : 最普通用词，一般指常住居民。
- a city of five million inhabitants
- the oldest inhabitant of the village
- Cairo has only thirteen square centimetres of green space for each inhabitant.
resident : 多指长期居住或暂时居住的民民，有时也指旅居者。
- a resident of the UK/Australia
- The local residents were angry at the lack of parking spaces.
- The hotel bar was only open to residents (= to people staying at the hotel).
native : 指土生土长的本地居民以及本地动物。
- a native of Monaco
- The red squirrel is a native of Britain.