Meaning of EITHER in English
/ ˈaɪðə(r); NAmE ; ˈiːðə(r)/ determiner , pronoun , adverb
■ determiner , pronoun
one or the other of two; it does not matter which :
You can park on either side of the street.
You can keep one of the photos. Either of them—whichever you like.
There are two types of qualification—either is acceptable.
➡ note at neither
each of two :
The offices on either side were empty.
There's a door at either end of the corridor.
used after negative phrases to state that a feeling or situation is similar to one already mentioned :
Pete can't go and I can't either.
( NAmE , informal )
'I don't like it.' 'Me either.' (= Neither do I) .
used to add extra information to a statement :
I know a good Italian restaurant. It's not far from here, either.
either ... or ... used to show a choice of two things :
Well, I think she's either Russian or Polish.
I'm going to buy either a camera or a DVD player with the money.
Either he could not come or he did not want to.
—compare or ➡ note at neither
Old English ǣgther , contracted form of ǣg(e)hwæther , of Germanic origin; ultimately related to aye and whether .
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005