Толковый словарь английского языка - either

I. adjective see: aye Date: before 12th century being the one and the other of two ; each , being the one or the other of two , II. pronoun Date: before 12th century the one or the other , III. conjunction Date: before 12th century — used as a function word before two or more coordinate words, phrases, or clauses joined usually by or to indicate that what immediately follows is the first of two or more alternatives guest room or as an office> IV. adverb Date: 15th century likewise, moreover, for that matter