'ardab' originates from Arabic, specifically the word 'ardab', where 'ardab' meant 'a unit of dry measure'.

'ardab' entered European usage via Medieval Latin and Old French forms such as 'ardabus' / 'ardeb', and eventually the form 'ardab' appeared in English usage.

Initially, it meant 'a unit for measuring dry goods (especially grain)', and over time it has retained that core meaning though the exact amount designated has varied by region.