'piscivorous' originates from Latin, specifically the word 'piscivorus,' where 'piscis' meant 'fish' and 'vorare' meant 'to devour.'

'piscivorus' (Latin) was used in New/Modern Latin to form scientific adjectives and was borrowed into English as 'piscivorous' (used in the 18th–19th century in biological contexts).

Initially it meant 'devouring fish' (literally 'fish-devouring'), and over time it has kept the meaning 'feeding on fish' in biological and general usage.