The word Nither is misspelled against Neither, an adjective meaning "Not either; not the one or the other."
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Word contains consecutive vowels 'EI' in between alphabets n & ther is misspelled as 'I' as letter 'E' is phonetically ignored
Wrong Spelling:  n-i-ther 
Correct Spelling:  n-ei-ther 
Find more wrongly spelled words of Neither to spell it well.