If "candidate" refers to someone running for a position:
* Loser: This is the most direct antonym, specifically meaning someone who did not win the election.
* Non-competitor: This emphasizes that someone is not vying for the position at all.
* Ineligible: This indicates someone who is not qualified to run for the position.
If "candidate" refers to someone being considered for something:
* Rejected: This indicates someone who was not chosen.
* Unqualified: This emphasizes that someone does not meet the requirements.
* Excluded: This implies someone was not considered for the position at all.
Other options:
* Opposer: This could be used if the context is about someone who opposes a candidate.
* Non-participant: This is more general, indicating someone who is not involved in the process at all.
Ultimately, the best antonym for "candidate" depends on the specific context of its use.