Definition of "either"

His flowing hair In curls on either cheek played.

1667, John Milton, “Book III”, in Paradise Lost. […], London: […] [Samuel Simmons], […]; republished as Paradise Lost in Ten Books: […], London: Basil Montagu Pickering […], 1873,

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

1936, Djuna Barnes, Nightwood, Faber & Faber, published 2007, page 31

I hope you will be ready to own publicly, whenever you shall be called to it, that by your great and frequent urgency you prevailed on me to publish a very loose and uncorrect account of my travels, with directions to hire some young gentleman of either university to put them in order, and correct the style, as my cousin Dampier did, by my advice, in his book called “A Voyage round the world.”

Jonathan Swift (1726) Gulliver's Travels, 1st edition

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 […] .

1748, [Samuel Richardson], “Letter LI”, in Clarissa. Or, The History of a Young Lady: […], volumes (please specify |volume=I to VII), London: […] S[amuel] Richardson; […]

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.

2013 September 7, Daniel Taylor, “Danny Welbeck leads England's rout of Moldova but hit by Ukraine ban”, in The Guardian‎

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

a. 1627 (date written), Francis [Bacon], “Considerations Touching a VVarre vvith Spaine. […]”, in William Rawley, editor, Certaine Miscellany VVorks of the Right Honourable Francis Lo. Verulam, Viscount S. Alban. […], London: […] I. Hauiland for Humphrey Robinson, […], published 1629

And either vowd with all their power and wit, / To let not others honour be defaste […]

1590, Edmund Spenser, “Book III, Canto I”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie

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

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

But Richmond […] appeared to lose himself in his own reflections. Some pickled crab, which he had not touched, had been removed with a damson pie; and his sister saw […] that he had eaten no more than a spoonful of that either.

1959, Georgette Heyer, chapter 1, in The Unknown Ajax

You can't be a table and a chair. You're either a Jew or a gentile.

2006 December 5, Jackie Mason, quotee, “Mason drops lawsuit vs. Jews for Jesus”, in USA Today

Thus, when he drew up instructions in lawyer language […] his clerks […] understood him very well. If he had written a love letter, or a farce, or a ballade, or a story, no one, either clerks, or friends, or compositors, would have understood anything but a word here and a word there.

1893, Walter Besant, “Prologue”, in The Ivory Gate