either vs neither

either

• Any one (of two). 

• Each of two; both. 

• As well. 

• One or the other of two people or things. 

• Introduces the first of two (or occasionally more) options or possibilities, the second (or last) of which is introduced by “or”. 

neither

• Not one of two; not either. 

• Not either (used with nor). 

• Similarly not. 

• Not either one of two.