neitheryoudaoicibaDictYouDict[neither 词源字典]
neither: [13] Despite the two words’ similarity, neither is not just either with a negative prefix tacked on. It comes ultimately from Old English nāhwæther ‘neither’, a compound formed from nā ‘not’ (which survives as no in modern English ‘whether or no’) and hwæther ‘which of two’ (ancestor of modern English whether). In the late Old English period it was contracted to nawther, and in Middle English, under the influence of either, this became transformed into neither.
=> whether[neither etymology, neither origin, 英语词源]
neither (conj.)youdaoicibaDictYouDict
Old English nawþer, contraction of nahwæþer, literally "not of two," from na "no" (see no) + hwæþer "which of two" (see whether). Spelling altered c. 1200 by association with either. Paired with nor from c. 1300; earlier with ne. Also used in Old English as a pronoun. As an adjective, mid-14c.