'annotate' originates from Latin, specifically the word 'annotare', where 'ad-' (often assimilated to 'an-') meant 'to/toward' and 'notare' meant 'to mark, note'.

'annotate' changed from the Medieval Latin word 'annotare' (and via Old French/Latin usage 'annoter') and eventually became the modern English word 'annotate' through later Medieval and early modern borrowings.

Initially, it meant 'to mark or note', but over time it evolved into its current meaning of 'to add explanatory notes or comments'.