'odious' originates from Latin, specifically the word 'odiosus', where 'odium' meant 'hatred'.

'odious' changed from Old French word 'odieus' (or 'odieus' in Anglo-Norman) and Middle English forms 'odius'/'odieus', and eventually became the modern English word 'odious'.

Initially, it meant 'full of hatred' or 'causing hatred', but over time it evolved into its current meaning of 'extremely unpleasant; arousing strong dislike'.