'apickaback' originates from Early Modern English, formed with the prefix 'a-' (meaning 'on') attached to 'pickaback' (from 'pick' + 'back'), where 'pick' (from Middle English 'pikken') meant 'to pick up' and 'back' (Old English 'bæc') meant 'the back (of the body)'.

'apickaback' developed from earlier expressions such as 'pick a back' and the single word 'pickaback' in Middle and Early Modern English; later the related verb and noun forms 'pickaback' and the variant 'piggyback' emerged, while the prefixed form 'a-pickaback' remained as a dialectal/archaic variant.

Initially it simply described the physical action or position 'on the back' and over time retained that basic meaning; its use became less common and more dialectal/archaic compared with 'piggyback' or 'pickaback'.