• enPR īth′ə(r), IPA: /ˈaɪð.ə(ɹ)/, /ˈiːð.ə(ɹ)/

1. Any one (of two).

   You can have it in either colour.

2. Each of two; both. [from 9th c.]

   There is a locomotive at either end of the train, one pulling and the other pushing.

   • 1667, John Milton, “Book 3”, in Paradise Lost. A Poem Written in Ten Books, London: Printed [by Samuel Simmons], and are to be sold by Peter Parker […] [a]nd by Robert Boulter […] [a]nd Matthias Walker, […], OCLC 228722708 ↗; republished as Paradise Lost in Ten Books: The Text Exactly Reproduced from the First Edition of 1667: […], London: Basil Montagu Pickering […], 1873, OCLC 230729554 ↗:

     His flowing hair / In curls on either cheek played.

   • 1936, Djuna Barnes, Nightwood, Faber & Faber 2007, page 31:

     Her hands, long and beautiful, lay on either side of her face.

3. (now, rare) Any one (of more than two).
   • 1748, Samuel Richardson, Clarissa, Letter 51:

     They entreat, they pray, they beg, they supplicate (will either of these do, Miss Clary?) that you will make no scruple to go to your uncle Antony's […].

• (each of two) both, each

• French: soit
• German: beide
• Italian: ciascuno
• Portuguese: ambos, qualquer um
• Russian: ка́ждый
• Spanish: cada

1. One or other of two people or things.

   He made me two offers, but I did not accept either.

   • 2013, Daniel Taylor, Danny Welbeck leads England's rout of Moldova but hit by Ukraine ban ↗, The Guardian, 6 September:

     Hodgson may now have to bring in James Milner on the left and, on that basis, a certain amount of gloss was taken off a night on which Welbeck scored twice but barely celebrated either before leaving the pitch angrily complaining to the Slovakian referee.

2. (obsolete) Both, each of two or more.
   • 1623, Francis Bacon, A Discourse of a War with Spain

     Scarce a palm of ground could be gotten by either of the three.

   • 1590, Edmund Spenser, The Faerie Qveene. […], London: Printed [by John Wolfe] for VVilliam Ponsonbie, OCLC 960102938 ↗, book III, canto I:

     And either vowd with all their power and wit, / To let not others honour be defaste {{...}

   • 1872', Oliver Wendell Holmes, Sr., The Poet at the Breakfast-Table

     There have been three famous talkers in Great British, either of whom would illustrate what I say about dogmatists.

either (not comparable)

1. (conjunctive, after a negative) As well.

   I don't like him, and I don't like her either.

• French: non plus
• German: auch
• Italian: neanche, nemmeno, neppure
• Portuguese: também não, tampouco
• Russian: та́кже не
• Spanish: tampoco

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

   Either you eat your dinner or you go to your room.

   You can have either potatoes or rice with that, but not both.

   You'll be either early, late, or on time.

• French: ou, soit
• German: entweder ... oder
• Italian: o, oppure
• Portuguese: ou...ou
• Russian: и́ли ... и́ли
• Spanish: o...o