'apeak' originates from Middle English, specifically the elements 'a-' (from Old English meaning 'on') and 'peak' (from Old English 'pēac' meaning 'point, summit'), where 'a-' meant 'on' and 'peak' meant 'summit'.

'apeak' changed from Middle English forms such as 'a-pek(e)' or phrases meaning 'on peak' and eventually remained in modern English as the rare/archaic word 'apeak'.

Initially, it meant 'on the peak', but over time it evolved into the current sense of 'at the top; upwards' and is now chiefly archaic or dialectal.