'lousewort' originates from English, specifically a compound of the words 'louse' and 'wort', where 'louse' meant 'a parasitic insect' and 'wort' meant 'plant'.

'lousewort' changed from Old English 'lūswyrt' through Middle English forms such as 'louswort' and eventually became the modern English word 'lousewort'.

Initially, it referred to a 'plant associated with or thought to cause lice' but over time it became the name for certain meadow and bog plants (for example species of Pedicularis and sometimes Rhinanthus).