'hornwort' originates from Old English, specifically the words 'horn' and 'wyrt', where 'horn' referred to the horn-like appearance of the plant's sporophytes and 'wyrt' meant 'plant' or 'herb'.

'hornwort' changed from the Old English word 'hornwyrt' and eventually became the modern English word 'hornwort'.

Initially, it meant 'a plant with horn-like structures', and this meaning has largely remained the same in modern usage.