Either \Ei"ther\ (?; 277), a. & pron. [OE. either, aither, AS. ?g?er, ?ghw[ae]?er (akin to OHG. ?ogiwedar, MHG. iegeweder); [=a] + ge + hw[ae]?er whether. See Each, and Whether, and cf. Or, conj.]

1. One of two; the one or the other; -- properly used of two things, but sometimes of a larger number, for any one.

Lepidus flatters both, Of both is flattered; but he neither loves, Nor either cares for him. --Shak.

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

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

2. Each of two; the one and the other; both; -- formerly, also, each of any number.

His flowing hair In curls on either cheek played. --Milton.

On either side . . . was there the tree of life. --Rev. xxii. 2.

The extreme right and left of either army never engaged. --Jowett (Thucyd).

Source: Webster's Revised Unabridged Dictionary (1913)
 

Either \Ei"ther\, conj. Either precedes two, or more, co["o]rdinate words or phrases, and is introductory to an alternative. It is correlative to or.

Either he is talking, or he is pursuing, or he is in a journey, or peradventure he sleepeth. --1 Kings xviii. 27.

Few writers hesitate to use either in what is called a triple alternative; such as, We must either stay where we are, proceed, or recede. --Latham.

Note: Either was formerly sometimes used without any correlation, and where we should now use or.

Can the fig tree, my brethren, bear olive berries? either a vine, figs?? --James iii. 12.

Source: Webster's Revised Unabridged Dictionary (1913)