'asteep' originates from Middle English, formed with the prefix 'a-' (from Old English prepositional/inchoative 'on' or 'in') attached to the adjective 'steep'.

'asteep' changed from Middle English forms like 'a-steep' (prefix 'a-' + 'steep'), ultimately tracing 'steep' back to Old English 'stēap' meaning 'high' or 'lofty'.

Initially, it meant 'on or in a steep place' (i.e., situated on a steep slope), but over time it has been used more generally to mean 'steep' or 'steeply' in descriptive or literary contexts.