atween

From Middle English atwene. Equivalent to a- +‎ twain.

atween

1. (archaic, dialectal) Between.

   Synonyms: atwixt, betwixt

   • 1816, John Keats, On Leaving Some Friends at an Early Hour:

     The silver strings of heavenly harp atween:
     And let there glide by many a pearly car,
     Pink robes, and wavy hair, and diamond jar

   • 1871, Elizabeth Stuart Phelps Ward, The Silent Partner:

     That's jest a specimen o' the kind of stoopidity as always seems to be a layin' atween property and poverty, atween capital and labor, atween you settin' thar with yer soft ways and yer soft dress ag'in you, and me, and the bed, and the chair, and the wall, and the end on't.

From Middle English atwene.

atween

1. between

• “atween” in the Dictionary of the Scots Language, Edinburgh: Scottish Language Dictionaries.