- either O.E. ægðer, contraction of æghwæðer "each of two, both," from a "always" (see AYE (Cf. aye) (2)) + ge- collective prefix + hwæðer "which of two, whether" (see WHETHER (Cf. whether)). Cognate with Du. ieder, O.H.G. eogiwedar, Ger. jeder "either, each, every"). Modern sense of "one or the other of two" is late 13c. Use of either-or to suggest an unavoidable choice between alternatives (1931) in some cases reflects Dan. enten-eller, title of an 1843 book by Kierkegaard.
Etymology dictionary. 2014.