'folivorous' originates from New Latin, specifically the word 'folivorus', where 'folium' meant 'leaf' and 'vorare' meant 'to devour'.

'folivorus' was formed from Latin elements 'folium' + 'vorare' and passed into scientific English (New Latin) as 'folivorus', later becoming the English adjective 'folivorous'.

Initially it meant 'devouring leaves' in a literal, descriptive sense; over time it has remained specialized and now commonly describes animals or organisms that eat leaves ('leaf-eating').