'annotation' originates from Latin, specifically the word 'annotatio', where the verb 'annotare' was formed from the prefix 'ad-' plus 'notare', and 'ad-' meant 'to' while 'notare' meant 'to mark or note'.

'annotation' changed from the Medieval Latin word 'annotatio' (from 'annotare') and entered English via Late Middle English, eventually becoming the modern English word 'annotation'.

Initially, it meant 'the act of making a note or marking', but over time it evolved into its current meaning of 'a note added to a text for explanation or comment'.