Where does “neother-” come from?

neother- (Middle English) comes from Old English niþer-, from Old English niþer, from Proto-Germanic niþer, from Proto-Indo-European niter.

Ancestry of “neother-”, step by step

Step	Language	Word	Meaning
1	Old English	niþer-	below, beneath; situated in a lower position,...
2	Old English	niþer	down; downstairs
3	Proto-Germanic	niþer	down, downwards
4	Proto-Indo-European	niter	—

neother- — Etymology, Origin & Word History | Etymology Explorer