'usurious' originates from Late Latin, specifically the word 'usurarius', where 'usura' meant 'use' or 'interest'.

'usurious' changed from Middle English/Old French forms related to 'usury' (Middle English 'usurie' from Old French 'usurie'), and the adjective was formed in English by adding the suffix '-ous' to create 'usurious'.

Initially connected to 'use' or 'interest' in a neutral sense (from Latin 'usura'), over time the term narrowed to refer specifically to charging excessive or illegal interest and now carries a negative moral judgment.