'appeach' originates from Middle English, specifically the word 'apechen', which in turn came from Anglo-French/Old French 'apechier', where the prefix 'a-' functioned as a verbal prefix and the root 'pech-/pechier' carried the sense 'to blame' or 'to accuse'.

'appeach' changed from Old French 'apechier' into Middle English 'apechen' and later appeared in Early Modern English as 'appeach'; over time the form 'impeach' became the dominant modern form and 'appeach' grew obsolete.

Initially it meant 'to accuse or call to account'; this basic sense has been retained but the specific form 'appeach' became rare/archaic, with 'impeach' used in modern English.