'annotator' originates from Latin, specifically the verb 'annotare', where the prefix 'ad-' (assimilated to 'an-') meant 'to/toward' and 'notare' meant 'to mark or note'.

'annotator' developed from Latin 'annotare' (to note) into Medieval/Church Latin forms such as 'annotare'/'annotator', passed into Middle English via Medieval Latin and French influences (e.g., Old/Middle French 'annoter'/'annoter'), and became the modern English 'annotator'.

Initially it meant 'to make a note' or 'to mark', and over time it came to mean specifically 'one who adds explanatory notes, comments, or labels' in modern usage.