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either

det. · pron. · conj. · adv.
US //ˈaɪðɝ// UK //ˈaɪðɐ// ei·ther
  1. 1 one of two (det.)
    A2 Elementary

    one or the other of two things or people.

    referring to any one of two people, things, or possibilities.

    Example

    You can park on either side of the street today.

    Example

    The candidate was equally qualified for either position, making the final selection process exceptionally difficult for the hiring committee.

    Usage

    Followed by a singular countable noun.

    Pitfall
    You can take either books.
    You can take either book.

    When used as a determiner before a noun, 'either' must be followed by a singular countable noun.

  2. 2 both (det.)
    B1 Intermediate

    each of two things.

    referring to each of two things, often used to describe things that come in pairs.

    Example

    There were tall trees on either side of the river.

    Example

    The guards stood at either end of the corridor, ensuring that no unauthorised personnel could enter the secure wing.

    Usage

    Followed by a singular countable noun.

    Teacher's tip

    In this sense, 'either' is more formal than 'both'.

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  1. 3 one or the other (pron.)
    A2 Elementary

    one of two people or things, used without naming the noun again.

    the one or the other of two people or things; functions as the head of a noun phrase.

    Example

    I have two pens; you can use either of them.

    Example

    If either of the proposed solutions fails to address the budget deficit, the board will be forced to consider more drastic measures.

    Usage

    Often followed by 'of' plus a plural noun or pronoun.

  2. 4 choice with 'or' (conj.)
    A2 Elementary

    used before the first of two choices to show a clear alternative.

    a correlative conjunction used to introduce the first of two or more alternatives, paired with 'or'.

    Example

    We can either go to the cinema or stay at home and watch a movie.

    Example

    The company must either invest heavily in new technology or risk losing its competitive advantage in the global market.

    Usage

    Pairs with 'or' to connect words, phrases, or clauses.

    Teacher's tip

    Ensure the elements following 'either' and 'or' are grammatically parallel.

  3. 5 also (in negative sentences) (adv.)
    A2 Elementary

    used at the end of a negative sentence to mean 'also'.

    used for emphasis after a negative statement to indicate that a further negative fact is also true.

    Example

    I don't like spicy food, and my sister doesn't like it either.

    Example

    The first experiment did not yield the expected results, and the subsequent trials were not successful either.

    Usage

    Typically placed at the end of a clause.

    Pitfall
    I don't like coffee too.
    I don't like coffee either.

    Use 'too' or 'also' in positive sentences, but use 'either' in negative sentences.

Origin

From Middle English either, from Old English ǣġhwæþer, from Proto-West Germanic aiw + gahwaþar. Akin to Old Saxon eogihwethar, iahwethar (Low German jeed); Old Dutch iogewether, iowether, *iother (Dutch ieder); Old High German eogihwedar, iegihweder, ieweder (German jeder).

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