neither

Từ điển American Heritage Dictionary 4th

nei·ther (nēʹthər, nīʹ-)adj.
Not one or the other; not either:
Neither shoe feels comfortable.pron.
Not either one; not the one or the other:
Neither of the twins is here. Neither will do. Neither of them is incorrect.conj.
1. Not either; not in either case. Used with the correlative conjunction nor:
Neither we nor they want it. She neither called nor wrote. I got neither the gift nor the card.
2. Also not:
If he won't go, neither will she.adv.
Similarly not; also not:
Just as you would not, so neither would they. [Middle English, from Old English nāwther, nāhwæther(influenced by æghwæther, ægther, either): nā, not; See ne in Indo-European Roots + hwæther, which of two; See kʷo- in Indo-European Roots.] 
Usage Note: According to the traditional rule, neither is used only to mean “not one or the other of two.” To refer to “none of several,” none is preferred: None (not neither) of the three opposition candidates would make a better president than the incumbent.·The traditional rule also holds that neither is grammatically singular: Neither candidate is having an easy time with the press. However, it is often used with a plural verb, especially when followed by of and a plural: Neither of the candidates are really expressing their own views.·As a conjunction neither is properly followed by nor, not or, in formal style: Neither prayers nor curses (not or curses) did any good. See Usage Note at either. See Usage Note at every. See Usage Note at he¹. See Usage Note at none. See Usage Note at nor¹. See Usage Note at or¹.