Archaic word meaning 'in two' or 'into two pieces,' expressing separation or division.
From Old English 'atweyn' or 'on twa' (in two), from 'at-' + 'twain' (two). 'Twain' comes from Old English 'twegen' meaning two.
'In two atwain' appears in Shakespeare and old poetry—it's so archaic that modern readers need the repetition to get it, but it was once the natural way to say 'split apart.'
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