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

2. (a. & pron.) Each of two; the one and the other; both; -- formerly, also, each of any number.

3. (conj. Either) precedes two, or more, coordinate words or phrases, and is introductory to an alternative. It is correlative to or.

a certain a deux an any any one anybody anyone anything atomic aught both correspondingly exclusive for two identically in kind in like manner in that way individual indivisible integral irreducible like like that like this likewise lone monadic monistic one similarly simple single singular so sole solid solitary tete-a-tete the two thus unanalyzable undivided uniform unique unitary whole