spelling contest vs spelldown

spelling contest and spelldown both are nouns.

Word	Noun	Adjective	Verb	Adverb
spelling contest	Yes	No	No	No
spelldown	Yes	No	No	No

As nouns, spelling contest and spelldown are synonyms defined as:

spelling contest and spelldown: a contest in which you are eliminated if you fail to spell a word correctly

Other synonyms of spelling contest include spelling bee.

spelling contest (noun)	spelldown (noun)
a contest in which you are eliminated if you fail to spell a word correctly	a contest in which you are eliminated if you fail to spell a word correctly