Webster's Revised Unabridged Dictionary · 1913

Betwixt

Betwixt ({not transcribed}) , preposition

[Old English betwix, bitwix, rarely bitwixt, Anglo-Saxon betweox, betweohs, betweoh, betwīh; pref. be- by + a form from Anglo-Saxon twā two. See Between.]

1.
In the space which separates; between.
From betwixt two aged oaks. — Milton
2.
From one to another of; mutually affecting.
There was some speech of marriage Betwixt myself and her. — Shakespeare
Collocations (1)
Betwixt and between , in a midway position; so-so; neither one thing nor the other. [Colloquial]