D defs.my
Entry 1 sense Webster, 1913

Twain

/(twān)/ · IPA /tweɪn/
01 a. & n. Two; -- nearly obsolete in common discourse, but used in poetry and burlesque.
  1. 1.
    Two; -- nearly obsolete in common discourse, but used in poetry and burlesque.
    “And whosoever shall compel thee to go a mile, go with him twain.” — Matt. v. 41.
    “When old winter split the rocks in twain.” Dryden.