non-voter       
noun [ C ] (also nonvoter) uk/ˌnɒnˈvəʊ.tər/ us/ˌnɑːnˈvoʊ.t̬ɚ/
 非选民
a person who does not vote or who does not have a legal right to vote, especially in an election
  When questioned, non-voters gave a number of different reasons for not casting a vote.
 Low turnout can have a significant impact on the result because of demographic differences between voters and nonvoters. 由于选民和非选民之间的人口差异,低投票率会对选举结果产生重大的影响。 
 - More examples
 - We need to try really hard to persuade those long-term nonvoters to turn out and vote for us.
 - Turning nonvoters into voters is a basic job of democracy.
 - She claims to be a non-voter on principle because the whole system is corrupt.
 - She feels strongly that if you are a non-voter, you are not showing the proper respect for democracy.
 - Can it be right to simply remove nonvoters from the electoral rolls?