Betwixt, a word that became rather generally used in the 1500’s, began as twixt in the 1300’s. The initial Old English word as betweox, with the initial be (bet) stemming from the Proto Germanic language representing by, and twa standing for ‘two’. The suffix ixt began as isk and is what is nowadays known as the suffix ‘ish’.
Why this word?
Because we use the word ‘between’ all the time; it is a widely used adverb and I believe we should all have an unused synonym for it. Just because it makes it more intriguing and somewhat more interesting! Also, avoiding the Old English scent spreading outwards from this word is very hard to do…
How to use betwixt?
Exactly in the same way you use the word between. If you’re asking me, being between jobs is an endless, sometimes characteristic situation; but being betwixt jobs sheds the speaker saying it with a completely different light!