'annat' originates from Latin, specifically the word 'annata', where 'annus' meant 'year' and 'annata' meant 'a year's (payment)'.

'annat' changed from Medieval/Latin 'annata' and Old French forms into Middle English 'annate' / 'annates', eventually appearing as the English term 'annat' with plural 'annats' or 'annates'.

Initially it meant 'a year's payment' (general annual payment); over time it became specialized to mean 'the first year's profits of an ecclesiastical benefice paid to the pope' (i.e., 'first fruits').