n. 二, 两, 一对

[ noun ]
two items of the same kind
<noun.quantity>

Twain \Twain\, a. & n. [OE. twein, tweien, tweyne, AS.
tw[=e]gen, masc. See {Two}.]
Two; -- nearly obsolete in common discourse, but used in
poetry and burlesque. ``Children twain.'' --Chaucer.

And whosoever shall compel thee to go a mile, go with
him twain. --Matt. v. 41.

{In twain}, in halves; into two parts; asunder.

When old winder split the rocks in twain. --Dryden.

{Twain cloud}. (Meteor.) Same as {Cumulo-stratus}.