'assize' originates from Old French, specifically the word 'assise', ultimately from Latin 'assidere', where 'ad-' (later assimilated to 'a-') meant 'to' and 'sedere' meant 'to sit'.

'assize' changed from Old French 'assise' (meaning a sitting or ordinance) and entered Middle English as 'assize', developing senses of a court session and of statutes or fixed rules issued at such sittings.

Initially, it meant 'a sitting' or 'session'; over time it came to mean specifically a judicial session (an assize court) and additionally the regulations or standards established at such sessions (e.g. assizes regulating weights and measures).