'auxiliatory' originates from Latin, specifically the words 'auxilium' (help) and Late Latin 'auxiliatorius', where the element 'auxili-' meant 'help, aid'.

'auxiliatory' changed from Late Latin 'auxiliatorius' into Medieval/early Modern Latin and Middle English forms such as 'auxiliatorie', and eventually became the modern English adjective 'auxiliatory'.

Initially, it meant 'pertaining to help or aid', and over time it has retained this core sense as 'providing assistance or support' in modern usage.