Learner's definition of NONSTARTER
1 informal : someone or something that will not be effective or successful — usually singular
Tax reform appears to be a nonstarter this year.
As a candidate, he's a nonstarter. [=he has no chance to succeed as a candidate]
She acknowledges that the proposal may be a political nonstarter.
2 US, sports : a player who is not chosen to play at the beginning of games : a player who is not one of the starters on a team