If you are undecided, you have not yet made a decision or judgment about something.

Are you still undecided about the new job? 对那份新工作你还在犹豫吗？

54 percent of voters were in favour, 30 percent against, and the rest were undecided. 54%的投票者赞成，30%的反对，其余的还在观望。

not decided or finished

The whole question is still undecided. 整个问题仍然悬而未决。