Any one (of two). / Each of two; both. / (now rare) Any one (of more than two).

One or the other of two people or things. / (obsolete) Both, each of two or more.

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

(conjunctive, after a negative) As well.

Alternative form of either-or

Describing a situation in which there are only two choices. / Describing a situation in which there is a choice between two different plans of action, but both together are not possible

Able to use either (right or left) hand, often equally well; ambidextrous.

Regardless of what happens (out of two possible situations).

plural of either-way offence

Synonym of hybrid offence