'atwixt' originates from Middle English, as a variant of 'betwixt', ultimately related to Old English elements 'be-' and 'twixt' (from 'twi-', meaning 'two').

'atwixt' changed from Middle English/Old English forms such as 'betwixt' and earlier 'betwixte' and eventually appeared as the variant 'atwixt' in Early Modern English.

Initially it meant 'in the space or interval between' and over time the basic meaning has remained 'between', though the form 'atwixt' has become archaic and largely replaced by 'between'.