'acorn' originates from Old English, specifically the word 'æcern', where 'æcern' meant 'fruit' or 'berry'.

'æcern' transformed into the Middle English word 'akorn', and eventually became the modern English word 'acorn'.

Initially, it meant 'fruit' or 'berry', but over time it evolved into its current meaning of 'the nut of the oak tree'.