candidate vs spoiler

candidate and spoiler both are nouns.

Word	Noun	Adjective	Verb	Adverb
candidate	Yes	No	No	No
spoiler	Yes	No	No	No

As nouns, spoiler is a hyponym of candidate; that is, spoiler is a word with a more specific, narrower meaning than candidate:

candidate: a politician who is running for public office
spoiler: a candidate with no chance of winning but who may draw enough votes to prevent one of the leading candidates from winning

Other hyponyms of candidate include dark horse, favorite son, running mate, stalking-horse, write-in, write-in candidate.

candidate (noun)	spoiler (noun)
someone who is considered for something (for an office or prize or honor etc.)	a hinged airfoil on the upper surface of an aircraft wing that is raised to reduce lift and increase drag
a politician who is running for public office	an airfoil mounted on the rear of a car to reduce lift at high speeds
	someone who takes spoils or plunder (as in war)
	a candidate with no chance of winning but who may draw enough votes to prevent one of the leading candidates from winning
	someone who pampers or spoils by excessive indulgence